-- ===================================================================

-- The Unified Inventory part of this code is:
-- Copyright (c) 2012 CoRNeRNoTe, Dean Montgomery
-- License: GPLv3

-- As this module incorporates GPL3 code,  the entire module is  GPL3.
-- However,  the  rest of the code is  (c) 2017-2021  OldCoder (Robert
-- Kiraly) and Poikilos (Jake Gustafson).

-- ===================================================================

-- "coderskins.fallback" should specify a  64x32 (not 64x64)  fallback
-- skin PNG file that's guaranteed to exist.

local modname = minetest.get_current_modname()
local modpath = minetest.get_modpath (modname)
local storage = minetest.get_mod_storage()

coderskins          = {}
coderskins.pages    = {}
coderskins.fallback = "player_character.png"
coderskins.textdir  = modpath .. "/textures/"

-- ===================================================================

-- This table  maps a player name to an overlay name or list  if,  and
-- only if,  a skin has been displayed for the player and the associa-
-- ted overlay(s) was/were added  (or  an attempt was made  to add it/
-- them) in the most recent visual update. In all other cases, the map
-- result is nil.

-- Presently, possible overlay names include:
--
--    musicbadge    -- for the music badge
--    ncmask        -- for the ncvirus mask
--    spacesuit     -- for the spacesuit

coderskins.overlay_name = {}
coderskins.force_update = false

-- ===================================================================

dofile (modpath .. "/skinlist.lua" )
dofile (modpath .. "/oldmap.lua"   )

-- ===================================================================

local cslog = function (s)
    if false then
        ocutil.log ("[coderskins] " .. s)
    end
end

-- ===================================================================

coderskins.png_exists  = function (str)
    return ocutil.png_exists  (modname, str)
end

-- ===================================================================

coderskins.png_missing = function (str)
    return ocutil.png_missing (modname, str)
end

-- ===================================================================

local get_stored_trbase = function (plname)
    if  ocutil.str_empty (plname) then
        ocutil.panic ("get_stored_trbase")
    end

    local trbase = storage:get_string (plname)
    if ocutil.str_empty (trbase) then return "" end
    return trbase
end

-- ===================================================================

local get_stored_skinpng = function (plname)
    local  trbase = get_stored_trbase (plname)
    if ocutil.str_empty (trbase) then return "" end
    return trbase .. ".png"
end

-- ===================================================================

local set_stored_trbase = function (plname, trbase)
    if  ocutil.str_empty (plname ) or
        ocutil.str_empty (trbase ) then
        ocutil.panic ("set_stored_trbase")
    end

    trbase = trbase:gsub ("%.png$", "")

    if  storage:get_string (plname) ~= trbase then
        storage:set_string (plname, trbase)
    end
end

-- ===================================================================

for plname, trbase in pairs (coderskins.oldmap) do
    local stored = get_stored_trbase (plname)

    if ocutil.str_empty (stored) then
        local skinpng = trbase .. ".png"
        if coderskins.png_exists (skinpng) then
            set_stored_trbase (plname, trbase)
        end
    end
end

-- ===================================================================

local function wstrim (s)
    return s:match "^%s*(.-)%s*$"
end

-- ===================================================================

coderskins.get_player_skin = function (plname)

    local fallback = coderskins.fallback
    local gps      = "coderskins.get_player_skin"
    local skinpng  = get_stored_skinpng (plname)

    cslog (plname .. ": stored skinpng is " .. skinpng)

    if  skinpng == "" or
        coderskins.png_missing (skinpng) then
        ocutil.log ("coderskins error: missing " .. skinpng)
        skinpng =  fallback
    end

    if coderskins.png_missing (skinpng) then
        ocutil.panic (gps .. " #1: missing " .. skinpng)
    end

    local pngpath = coderskins.textdir .. skinpng
    local w, h    = ocutil.get_png_dim (pngpath)

    if w == nil or w ~= 64 or
       h == nil or (h ~= 32 and h ~= 64) then
       cslog (plname .. ": ocutil.get_png_dim failed")
       if skinpng == fallback then ocutil.panic (gps .. " #2") end
       return fallback, 32
    end

    cslog (plname .. ": found and using file " .. skinpng)
    return skinpng, h
end

-- ===================================================================

coderskins.get_player_skin32 = function (plname)
    local skinpng = coderskins.get_player_skin (plname)
    return "[combine:64x32:0,0=" .. skinpng, 32
end

-- ===================================================================

local get_overlaypng = function (overlay_name)
    if ocutil.ends_with (overlay_name, ".png") then
        return overlay_name
    end

    return "coderskins_" .. overlay_name .. "_overlay.png"
end

-- ===================================================================

-- This is a list of Lua patterns (not shell globs) to be applied to a
-- PNG-file name. If there is a match, the PNG file is treated as tho-
-- ugh it's likely to be transparent.

coderskins.blanks = {
    ".*transparent.*" , ".*trans%.png"
}

-- ===================================================================

-- In "coderskins.get_first_texture":

-- "iostr" (short for "image_or_overlay_string") is a string that con-
-- tains  one or more image-file names (including filename extensions)
-- and/or "^[" MT Lua API operation strings.

-- At least one non-transparent image file must be specified.

-- This  function  returns the name  (including filename extension) of
-- the first non-transparent image file.

-- The name in question must come before the first "^[" operation str-
-- ing (if any) in "iostr". Additionally, the "^[" operations (if any)
-- shouldn't change  the aspect ratio (i.e., ratio of width to height)
-- of the image in question.

-- The  purpose of this routine is to simplify  higher-level code that
-- depends on aspect ratios.

-- This routine  is recursive.  "debug_indent"  should be omitted  (or
-- nil) in the  highest-level call.  It's  used internally by the rou-
-- tine in subsequent recursive calls.

-- ===================================================================

coderskins.get_first_texture = function (iostr, debug_indent)

    if  debug_indent == nil then
        debug_indent =  ""
    end

    local ender_i = iostr:find ("%^")
    -- ^ "The character % works as an escape character"
    --   -<https://www.lua.org/manual/5.3/manual.html>

    if ender_i ~= nil then
        if ender_i > 1 then
            local filename = iostr:sub (1, ender_i - 1)

            if  ocutil.match_any_pattern (iostr,
coderskins.blanks) ~= nil then

-- 210916 Poikilos says: A transparent texture here is irrelevant (and
-- is often a random size and ratio).

                cslog ("" ..
debug_indent .. "- \"" ..
iostr   ..
"\" so instead getting image size from: " ..
iostr:sub (ender_i+1))

return coderskins.get_first_texture (iostr:sub (ender_i+1),
debug_indent .. "  ")
            end

            cslog ("" ..
"- first texture (not transparent): " ..
iostr:sub (1, ender_i))

            return filename
        else
            cslog ("" ..
"The image couldn't be detected" ..
" since the overlay \"" .. iostr ..
"\" started with ^ (at " .. ender_i .. ") not an image.")
        end
    end

    return iostr
end

-- ===================================================================

-- In "coderskins.find_texture_size":

-- "filename" is a string  in the same format as the "iostr" parameter
-- used by "coderskins.get_first_texture".

-- An additional rule is imposed.  The name of the first non-transpar-
-- ent image file in the string must be in the following format:

-- MT "mod"  name  followed by underscore,  a descriptive string,  and
-- finally a filename extension (such as ".png").  The "mod" name  it-
-- self can include underscores  but shouldn't start or end with them.
-- Example: coderskins_ncmask_overlay.png

-- The  "mod" in question  must  have been  loaded prior  to the point
-- where this function is called.

-- This  function returns a 2-element list.  The list  consists of the
-- width and height of the image discussed above  or nil, nil if some-
-- thing does wrong.

-- ===================================================================

coderskins.find_texture_size = function (filename)
    filename = coderskins.get_first_texture (filename)
    local this_mod_path = ocutil.modpath_from_filename (filename)

    if this_mod_path ~= nil then
        local tmp_w, tmp_h = nil, nil

        if this_mod_path ~= nil then
            tmp_w, tmp_h = ocutil.get_png_dim (this_mod_path ..
"/textures/" .. filename)

            if tmp_w ~= nil then
                return tmp_w, tmp_h
            else
                cslog ("" ..
"\"" .. this_mod_path ..
"/textures/\" didn't contain \"" ..
filename .. "\"")
            end
        else
            cslog ("" ..
"The filename \"" ..
this_mod_path     ..
"\" isn't prefixed with a mod name, " ..
"so the texture path can't be detected.")
        end

        tmp_w, tmp_h = ocutil.get_png_dim (coderskins.textdir ..
filename)
        if tmp_w ~= nil then
            return tmp_w, tmp_h
        end
    end

    return nil, nil
end

-- ===================================================================

-- If the specified  player  is online,  this routine updates the dis-
-- played skin to match the recorded one.

-- "overlay_name"  may  be an  overlay name, a list of such names,  or
-- nil. Possible overlay names are listed earlier in this file.

-- If it's a list of such names,  the names must be in canonical order
-- as defined in the "default" mod.

-- If  it's a name or a list,  this routine attempts to add the speci-
-- fied overlay(s) to the skin displayed.

-- "coderskins.overlay_name" maps a player name to an overlay name (or
-- list) if and  only if  such an  attempt was made in the most recent
-- update for the player in question.

-- ===================================================================

-- 210906 RJK and Poikilos: Changes to this routine:
--
-- Previously,  if an overlay was applied to a square skin,  this code
-- dropped the lower half of the skin.  This was a kludge. We've dele-
-- ted that code.
--
-- Additionally,  this code  has been reworked to support various com-
-- binations of skin shape and overlay shape:
--
-- rectangle and rectangle -- typically 64x32 and 64x32
-- square    and rectangle -- typically 64x64 and 64x32
-- rectangle and square    -- typically 64x32 and 64x64
-- square    and square    -- typically 64x64 and 64x64

-- Note: The use of  the word "overlay"  in this code is a simplifica-
-- tion.  In fact, images are not directly  "overlaid" on  top of each
-- other  but  the net effect is similar for pieces of  CoderSkins ar-
-- mor.

-- ===================================================================

-- To explain further:

-- A 3D model typically has an associated "materials" array. Each mat-
-- terials array contains one or more "material" entries.  We'll refer
-- to such entries as "materials" for short.

-- Early "materials" stored color, "shininess", "roughness",  and "al-
-- pha".  These days,  they store a number of additional properties as
-- well.

-- A "material ID" is an index in the materials array. Note: The first
-- index may be 0, 1, or something else depending on the platforms us-
-- ed.

-- Each polygon in a model is assigned a material ID. Note: Many poly-
-- gons may share the same material ID.

-- ===================================================================

-- There's a  face-list which defines the polygons that are to be used
-- in a given model. The face-list  doesn't directly specify the loca-
-- tions of the polygons in 3-space. It references external vertex da-
-- ta which stores that information.

-- Each face-list entry typically stores one material ID and 3 or more
-- vertex IDs (where each vertex ID identifies the 3-space location of
-- one vertex in the vertex data).

-- ===================================================================

-- In the 1980s,  a supplemental mechanism known as "UV maps" evolved.
-- The "UV maps" approach works like this:

-- A 3D model  typically has one or more "model texture" images.  Each
-- may  contain multiple types of practical textures  (such as "brick"
-- or "grass") combined to produce a single larger image.

-- The textures may be organized, in each model texture image, in dif-
-- ferent  ways.  It  isn't  necessarily  as simple as paste  a set of
-- square  practical textures together to produce a larger  model tex-
-- ture.

-- A  3D model typically has  one or more "UV maps".  Each UV map is a
-- definitions table that lists sets of 2D polygons.

-- In the modern era, "materials" entries specify  exactly one UV map.
-- So, a face-list entry indirectly specifies one UV map by way of the
-- materials ID that it [the face-list entry] stores.

-- The  2D-space  polygons stored at the UV-map level need  to line up
-- with the 3D-space polygons  stored at the face-list and vertex-data
-- level to the following extent:
--
-- The number of polygons needs to be the same.
-- The side count for corresponding polygons needs to be the same.
-- Corresponding vertexes need to be listed in the same order.

-- A UV map  is used as follows:  Sub-regions  in  a  particular shape
-- associated with the UV map are  copied  out  of the  model  texture
-- associated with the UV map.  One  sub-region is  copied for each of
-- the 2D-space polygons in the UV map.  It's used to fill  the corre-
-- sponding 3D-space polygon.

-- ===================================================================

-- There may be multiple UV maps. This is due to the fact that each UV
-- map is designed  to select texture image subregions  of a different
-- shape  and a  particular model  may need to use  multiple shapes in
-- this context.

-- ===================================================================

-- "UV maps"  aren't absolutely required but  their use became  common
-- after the 1980s.  Poikilos cites the rise of CGI in movies starting
-- in that decade as a turning point:

-- "For  anything that wasn't supposed to look abstract,  UV maps were
-- pretty much necessary."

-- The most advanced  use of  non-UV map models in movies was probably
-- in the 1982 film "Tron". You generally need to use UV-maps for any-
-- thing much beyond "Tron" that needs to fit visually into a concrete
-- world."

-- "Young Sherlock Holmes" (1985) was  an early  example of the use of
-- UV maps in CGI.  The stained-glass creature in that film was model-
-- ed using this mechanism."

-- ===================================================================

-- The  older Minetest 3D character models were based on just a single
-- material ID.  It allowed the use of a single UV map to put a "skin"
-- on a character.

-- In 2013, "StuJones11" created a "3D Armor" mod that used 3 material
-- IDs:
--
-- ID #1 or "pngim_rect":  The model texture image used is a 2:1 ratio
-- image (such as 64x32).  It defines a low-resolution skin similar to
-- old Minecraft skins.
--
-- ID #2 or "pngim_armor:  The model texture image used is a 2:1 ratio
-- image (such as 64x32) again.  It's  used in conjunction  in a 64x32
-- skin and adds armor.

-- Some types of armor  go,  in a type-2 texture, in the same place as
-- the corresponding body parts in the 64x32  skin.  Other types [such
-- as shields] go at unique reserved locations in the overlay.

-- ID #3 or "pngim_wield": The model texture image used is a 1:1 ratio
-- image (typically 16x16).

-- Note:  "pngim_wield" is different than  the Minetest  API's "wield-
-- item" feature. "wielditem" only applies to the simplified  HUD ver-
-- sion  of the character model  that is part of the Minetest core en-
-- gine.

-- Sizes larger  than 16x16 may have a negative effect on the  "wield-
-- item" feature.

-- In 2017, Jordach aka Maciej Kasatkin implemented a material that he
-- assigned material ID #2 to.  This conflicted with the StuJones11 ID
-- set and so Jordach's change  wasn't compatible with 3D Armor.  Jor-
-- dach's ID #2 material was as follows:
--
-- ID #2: The model texture image used was a 1:1 ratio image  (such as
-- 64x64).  It defined  a high-resolution skin similar to  newer Mine-
-- craft skins.

-- OldCoder  subsequently  made 3D Armor and  Jordach's enhanced skins
-- work together  through the simple kludge of truncating  64x64 skins
-- to  64x32 when players put on items 3D Armor.  This sacrificed  de-
-- tails, of course.

-- In 2021,  Poikilos moved Jordach's  ID #2 to ID #4 and made various
-- changes to  Bucket Game and 3D Armor.  The  result was a MT "_game"
-- that supported all 4 "material" types as well as both MT 4 and MT 5
-- clients at the same time.

-- ===================================================================

coderskins.change_skin = function (plname, overlay_name)
    coderskins.force_update = false

    cslog ("change_skin(" .. plname .. ", ...)...")
    local player = minetest.get_player_by_name (plname)
    if player == nil then return end

    local show_overlay = false
    if overlay_name ~= nil then
          show_overlay = true
    end

    local skinpng = coderskins.get_player_skin (plname)
    local pngpath = coderskins.textdir .. skinpng

    local skin_width, skin_height = ocutil.get_png_dim (pngpath)
    local pngim_rect   = ""
    local pngim_armor  = ""
    local pngim_wield  = ""
    local pngim_square = ""

    if skin_width == nil then
        cslog ("Invalid PNG file: " .. pngpath)
        return
    end

    if skin_width / skin_height == 2 then
        pngim_rect   = skinpng
    elseif skin_width / skin_height == 1 then
        pngim_square = skinpng
    end

    if show_overlay then
        if type (overlay_name) ~= "table" then
            overlay_name = { overlay_name }
        else
            overlay_name = ocutil.sort_first (overlay_name,
"3d_armor" )
            overlay_name = ocutil.sort_last  (overlay_name,
"badge"    )
        end

        for _,  oname in ipairs (overlay_name) do
            local this_o = get_overlaypng (oname)
            local this_w, this_h = coderskins.find_texture_size (this_o)

            if this_w ~= nil then
                if this_w / this_h == 2 then
pngim_armor  = ocutil.combine_images (pngim_armor,
this_o)
                    cslog ("- overlaying \"" ..
this_o .. "\" onto pngim_armor \""  .. pngim_armor .. "\"")
                elseif this_w / this_h == 1 then
pngim_square = ocutil.combine_images (pngim_square,
this_o)
                    cslog ("- overlaying \"" ..
this_o .. "\" onto pngim_square \"" .. pngim_square .. "\"")
                end
            else
                cslog ("Invalid PNG file: " .. this_o)
            end
        end
    end

    coderskins.overlay_name [plname] = overlay_name
    if rawget (_G, "armor") then
           pngim_wield =   armor.textures [plname].wielditem
        if pngim_wield == nil then pngim_wield = "" end
    end

    local pt = "ptextures_transparent.png"
    if pngim_rect   == "" then pngim_rect   = pt end
    if pngim_armor  == "" then pngim_armor  = pt end
    if pngim_wield  == "" then pngim_wield  = pt end
    if pngim_square == "" then pngim_square = pt end

    cslog ("" .. plname ..
" pngim_rect:"   .. pngim_rect  ..
" pngim_armor:"  .. pngim_armor ..
" pngim_wield:"  .. pngim_wield ..
" pngim_square:" .. pngim_square)

    player:set_properties ({
        textures = { pngim_rect  , pngim_armor  ,
                     pngim_wield , pngim_square }
    })
end

-- ===================================================================

local labmap = {}

labmap ["09sharkboy" ] = "skin_09SharkBoy"
labmap ["athena"     ] = "skin_Athena"
labmap ["brianna"    ] = "skin_Brianna_Playz"
labmap ["cat"        ] = "skin_Actual_Cat"
labmap ["chad"       ] = "skin_Chad_Wild_Clay"
labmap ["chara"      ] = "skin_Chara"
labmap ["cola"       ] = "skin_Cola"
labmap ["corona"     ] = "skin_Corona"
labmap ["cylon"      ] = "skin_Gold_Cylon"
labmap ["duck"       ] = "skin_Duck"
labmap ["elsa"       ] = "skin_Queen_Elsa"
labmap ["hotdog"     ] = "skin_Hotdog"
labmap ["kata"       ] = "skin_Kata_Red_Hair"
labmap ["kermit"     ] = "skin_Business_Kermit"
labmap ["ldshadow"   ] = "skin_LDShadow_Lady"
labmap ["luigi"      ] = "skin_Luigi"
labmap ["mario"      ] = "skin_Mario"
labmap ["moose"      ] = "skin_MooseCraft"
labmap ["offwhite"   ] = "skin_Chinese_Off_White"
labmap ["pizzagirl"  ] = "skin_Pizza_Girl"
labmap ["polarbear"  ] = "skin_Polar_Bear"
labmap ["potion"     ] = "skin_Potion_Master"
labmap ["preston"    ] = "skin_Preston_Playz"
labmap ["purple"     ] = "skin_Purple_Outfit"
labmap ["robocop"    ] = "skin_Robocop"
labmap ["rosalyn"    ] = "skin_Rosalyn_Potion_Master"
labmap ["stampy"     ] = "skin_Stampy_Boots"
labmap ["steampunk"  ] = "skin_Steampunk"
labmap ["superjack"  ] = "skin_Super_Jack"
labmap ["tiger"      ] = "skin_Tiger"
labmap ["tree"       ] = "skin_Apple_Tree"

-- ===================================================================

for skin_label, trbase in pairs (labmap) do
    local skinpng = trbase .. ".png"
    if not coderskins.png_exists (skinpng) then
        cslog ("Dropping skin label " .. skin_label)
        labmap [skin_label] = nil
    end
end

local label_to_trbase = labmap
local trbase_to_label = ocutil.swap_key_value (labmap)
local sorted_labels   = ocutil.ktable_to_vtable (labmap)
labmap = nil

-- ===================================================================

for key, value in pairs (sorted_labels   ) do
    cslog ("sorted_labels: "    .. key .. " => " .. value)
end

for key, value in pairs (trbase_to_label ) do
    cslog ("trbase_to_label: " .. key .. " => " .. value)
end

-- ===================================================================

local prompt = "Use e.g. /skin superjack" ..
    " to choose one of these:"

-- ===================================================================

local param_skins = {
    description = "list or change your own skins" ,
    params      = "skin name (optional)"          ,
    privs       = {}                              ,

    func = function (plname, params)

        local print_prompt = true
        local skin_label  = params
        local trbase

        if ocutil.str_empty (skin_label) then skin_label = "" end
        skin_label = skin_label:gsub ("%.png$", "")

        if ocutil.str_empty (skin_label) then
            trbase = get_stored_trbase (plname)

            if  ocutil.str_nonempty (trbase) then
                cslog ("player " .. plname .. " has trbase " ..
                    trbase)

                local old_label = trbase_to_label [trbase]
                if ocutil.str_empty (old_label) then
                      old_label = trbase
                end

                if ocutil.str_nonempty (old_label) then
                    print_prompt = false
                    minetest.chat_send_player (plname,
"Presently, your skin is " .. old_label .. ". " .. prompt)
                end
            end

            if print_prompt then
                minetest.chat_send_player (plname, prompt)
            end

            local buf    = ""
            local npline = 13
            local noline =  0

            for _, skin_label in pairs (sorted_labels) do
                buf    = buf .. " " .. skin_label
                noline = noline + 1

                if noline >= npline then
                    minetest.chat_send_player (plname, buf)
                    buf    = ""
                    noline = 0
                end
            end

            if noline > 0 then
                minetest.chat_send_player (plname, buf)
            end
            return
        end

        trbase = label_to_trbase [skin_label]

        if  trbase == nil then
            local xp = skin_label:gsub ("%.png$", "") .. ".png"
            if coderskins.png_missing (xp) then
                xp = "skin_" .. xp
                if coderskins.png_missing (xp) then
                    xp = xp:gsub ("^skin_", "player_")
                    if coderskins.png_missing (xp) then
                        minetest.chat_send_player (plname,
"Not a valid skin label")
                        return
                    end
                end
            end
            trbase = xp:gsub ("%.png$", "")
        end

        if coderskins.png_missing (trbase .. ".png") then
            minetest.chat_send_player (plname,
"Sorry, PNG file is missing")
            return
        end

        local oname = coderskins.overlay_name [plname]
        set_stored_trbase (plname, trbase)
        coderskins.change_skin (plname, oname)

        minetest.chat_send_player (plname,
"O.K. your skin has been changed to " .. skin_label)
    end
}

minetest.register_chatcommand ("skin"  , param_skins )
minetest.register_chatcommand ("skins" , param_skins )

-- ===================================================================

minetest.register_privilege ("skin", {
    description = "Can change skins for other players" ,
    give_to_singleplayer=true
})

-- ===================================================================

local param_playerskins = {
    description = "list or change skins for a player" ,
    params      = "<player> <skin_label>"             ,
    privs       = { skin=true }                       ,

    func = function (adname, params)

        local plname, label = string.match (params,
            "^([^ ]+) *(.*)")

        if not plname then plname = params end
        if ocutil.str_empty (plname) then plname = "" end
        if ocutil.str_empty (label ) then label  = "" end

        plname = plname:gsub (" +$", "")
        label  = label:gsub  (" +$", "")

        if ocutil.str_empty (plname) then
            core.chat_send_player (adname,
                "Usage: /pskin player_name skin_label")
            return true
        end

        if not core.get_auth_handler().get_auth (plname) then
            core.chat_send_player (adname,
                "Error: No such player: " .. plname)
            return true
        end

        local print_prompt = true
        local skin_label   = label
        local trbase

        if ocutil.str_empty (skin_label) then skin_label = "" end
        skin_label = skin_label:gsub ("%.png%", "")

        if ocutil.str_empty (skin_label) then
            trbase = get_stored_trbase (plname)

            if  ocutil.str_nonempty (trbase) then
                cslog ("player " .. plname .. " has trbase " ..
                    trbase)

                local old_label = trbase_to_label [trbase]
                if ocutil.str_empty (old_label) then
                      old_label = trbase
                end

                if ocutil.str_nonempty (old_label) then
                    print_prompt = false
                    minetest.chat_send_player (adname,
"Presently, their skin is " .. old_label .. ". " .. prompt)
                end
            end

            if print_prompt then
                minetest.chat_send_player (adname, prompt)
            end

            local buf    = ""
            local npline = 13
            local noline =  0

            for _, skin_label in pairs (sorted_labels) do
                buf    = buf .. " " .. skin_label
                noline = noline + 1

                if noline >= npline then
                    minetest.chat_send_player (adname, buf)
                    buf    = ""
                    noline = 0
                end
            end

            if noline > 0 then
                minetest.chat_send_player (adname, buf)
            end
            return
        end

        trbase = label_to_trbase [skin_label]

        if  trbase == nil then
            local xp = skin_label:gsub ("%.png$", "") .. ".png"
            if coderskins.png_missing (xp) then
                xp = "skin_" .. xp
                if coderskins.png_missing (xp) then
                    xp = xp:gsub ("^skin_", "player_")
                    if coderskins.png_missing (xp) then
                        minetest.chat_send_player (adname,
"Not a valid skin label")
                        return
                    end
                end
            end
            trbase = xp:gsub ("%.png$", "")
        end

        if coderskins.png_missing (trbase .. ".png") then
            minetest.chat_send_player (adname,
"Sorry, PNG file is missing")
            return
        end

        local oname = coderskins.overlay_name [plname]
        set_stored_trbase (plname, trbase)
        coderskins.change_skin (plname, oname)

        minetest.chat_send_player (adname,
"O.K. their skin has been changed to " .. skin_label)
    end
}

minetest.register_chatcommand ("playerskin" , param_playerskins )
minetest.register_chatcommand ("pskin"      , param_playerskins )

-- ===================================================================

minetest.register_on_joinplayer (function (player)

    local plname  = player:get_player_name()
    local skinpng = "player_" .. plname .. ".png"
    local final   = nil

-- ===================================================================

    coderskins.overlay_name [plname] = nil

-- ===================================================================

    if coderskins.png_exists (skinpng) then
        cslog (plname .. ": " .. skinpng .. " exists")
        final = skinpng
    else
        cslog (plname .. ": " .. skinpng .. " doesn't exist")
    end

-- ===================================================================

    if final == nil then
        skinpng = get_stored_skinpng (plname)

        if ocutil.str_empty (skinpng) then
            cslog (plname .. " doesn't have a recorded skin")
        else
            cslog (plname .. " has a recorded skin: " .. skinpng)

            if coderskins.png_exists (skinpng) then
                cslog (plname .. ": " .. skinpng .. " exists")
                final = skinpng
            else
                cslog (plname .. ": " .. skinpng .. " doesn't exist")
            end
        end
    end

-- ===================================================================

    if final == nil then
        local rslist = {
"Actual_Cat"        ,
"Apple_Tree"        ,
"Battery"           ,
"Bear"              ,
"Cola"              ,
"Fox"               ,
"Heather_Elf"       ,
"Lego_Person"       ,
"Lego_Spaceman"     ,
"Marley_Xia"        ,
"Puppy"             ,
"Rabbit_Coco"       ,
"Squirrel"          ,
"Steampunk"         ,
"Superpollo"        ,
"Tiger"             ,
        }

        cslog ("Setting initial skin for " .. plname)

        local ii       = math.random (#rslist)
        local charname = rslist [ii]
        skinpng        = "skin_" .. charname .. ".png"
        cslog (plname .. ": Selected " .. skinpng .. " at random")

        if coderskins.png_exists (skinpng) then
            cslog (plname .. ": " .. skinpng .. " exists")
            final = skinpng
        else
            cslog (plname .. ": " .. skinpng .. " doesn't exist")
        end
    end

-- ===================================================================

    if final == nil then
        skinpng = coderskins.fallback
        cslog (plname .. ": Falling back to " .. skinpng)

        if coderskins.png_exists (skinpng) then
            cslog (skinpng .. " exists")
            final = skinpng
        else
            ocutil.panic (skinpng .. " doesn't exist")
        end
    end

-- ===================================================================

    cslog ("Final skin for " .. plname .. " is " .. final)
    set_stored_trbase (plname, final)
    coderskins.change_skin (plname)
end)

-- ===================================================================

-- "skin" here is a base skin-file name that omits pathname component,
-- "_preview*" part, and ".png".

local list_pfront = {}

local get_pfront  = function (skin)

    local pfront  = list_pfront [skin]
    if pfront ~= nil then return pfront end

    pfront   = skin .. "_preview.png"
    local fp = io.open (coderskins.textdir .. pfront)

    if fp == nil then
        pfront = "coderskins_not_avail.png"
    else
        fp:close()
    end

    list_pfront [skin] = pfront
    return pfront
end

-- ===================================================================

-- "skin" here is a base skin-file name that omits pathname component,
-- "_preview*" part, and ".png".

local list_pback = {}

local get_pback  = function (skin)

    local pback  = list_pback [skin]
    if pback ~= nil then return pback end

    pback    = skin .. "_preview_back.png"
    local fp = io.open (coderskins.textdir .. pback)

    if fp == nil then
        pback = "coderskins_not_avail.png"
    else
        fp:close()
    end

    list_pback [skin] = pback
    return pback
end

-- ===================================================================
-- Display current skin.

local param_main_page = {
    get_formspec = function (player)

        local plname   = player:get_player_name()
        local skinpng  = get_stored_skinpng (plname)
        local noext    = skinpng:gsub ("%.png", "")

        local pfront   = get_pfront (noext)
        local pback    = get_pback  (noext)

        local desc1    = coderskins.desc1 [noext]
        local desc2    = coderskins.desc2 [noext]

        if ocutil.str_empty (desc1) then
            local filedesc
            filedesc = noext:gsub ("sdskin_" , "")
            filedesc = noext:gsub ("skin_"   , "")

            filedesc = filedesc:gsub ("sscharacter_" , "SS #"     )
            filedesc = filedesc:gsub ("uskins_"      , "uskins #" )
            filedesc = filedesc:gsub ("_"            , " "        )
            desc1    = filedesc
        end

        if ocutil.str_empty (desc2) then desc2 = "" end

                                -- Zero -based page number
        local zbpage = coderskins.pages [plname]
        if    zbpage == nil then zbpage = 0 end

        local formspec =
"background[0.06,0.99;7.92,7.52;ui_misc_form.png]" ..
"image[0,.75;1,2;" .. pfront  .. "]" ..
"image[1,.75;1,2;" .. pback   .. "]" ..
"label[2.4,.75;"   .. desc1   .. "]" ..
"label[2.4,1.25;"  .. desc2   .. "]" ..
"label[6,.5;Raw texture:]"           ..
"image[6,1;2,1;"   .. skinpng .. "]" ..
"button[.75,3;6.5,.5;coderskins_page_" .. zbpage .. ";Change]"

        return { formspec = formspec }
    end ,
}

unified_inventory.register_page ("coderskins", param_main_page)

-- ===================================================================

local param_main_button = {
    type    = "image"                 ,
    image   = "coderskins_button.png" ,
    tooltip = "CoderSkins"            ,
}

unified_inventory.register_button ("coderskins", param_main_button)

-- ===================================================================
-- Create the skin-picker pages.

local nsskins = #coderskins.list
local nspages = math.floor (nsskins / 16)
if    nsskins % 16 ~= 0 then
      nspages = nspages + 1
end
if    nspages > 99 then
      nspages = 99
end

cslog ("number of skins is "      .. nsskins)
cslog ("number of skin pages is " .. nspages)

for x = 0, nspages do
    unified_inventory.register_page ("coderskins_page_" .. x, {

        get_formspec = function (player)
            local plname = player:get_player_name()

                                -- Zero -based page number
            local zbpage = coderskins.pages [plname]
            if    zbpage == nil then zbpage = 0 end
                                -- One  -based page number
            local obpage = zbpage + 1

            local formspec =
"background[0.06,0.99;7.92,7.52;ui_misc_form.png]"

            local index = 0
            local skip  = 0 -- Skip coderskins, used for pages

            -- Skin thumbnails
            for i, x_skin in ipairs (coderskins.list) do
                local skin = x_skin:gsub (".png", "")

                if skip < zbpage*16 then skip = skip+1 else
                    if index < 16 then
                        local pfront = get_pfront (skin)

                        formspec = formspec ..
"image_button[" ..
(index % 8) .. "," ..
((math.floor (index / 8))*2) .. ";1,2;" .. pfront

                        formspec = formspec ..
";coderskins_set_" .. i .. ";]"
                    end
                    index = index+1
                end
            end

            -- "Prev" page button
            if zbpage > 0 then
                formspec = formspec ..
"button[0,4;1,.5;coderskins_page_" .. (zbpage-1) .. ";<<]"
            else
                formspec = formspec ..
"button[0,4;1,.5;coderskins_page_"  .. zbpage    .. ";<<]"
            end

            if false then
                formspec = formspec    ..
"button[.75,4;6.5,.5;coderskins_page_" ..
zbpage .. ";Page " .. obpage .. "/"    .. nspages .. "]"
            else
               local pba, pbx, pbz, pbq

               if     obpage  > 1 then
                   pbq  = "button[1,4;1,.5;coderskins_page_0;01]"
                   formspec = formspec .. pbq
               elseif nspages > 3 then
                   pbq  = "button[1,4;1,.5;coderskins_page_1;02]"
                   formspec = formspec .. pbq
               end

               if nspages >= 6 then
                   pba  = math.floor ((nspages / 3) + 0.5)
                   if pba <  1 then pba = 1 end
                   pbx  = tostring (pba)
                   if pba < 10 then pbx = "0"     .. pbx end
                   pbz  = tostring (pba-1) .. ";" .. pbx .. "]"
                   pbq  = "button[2,4;1,.5;coderskins_page_" .. pbz
                   formspec = formspec .. pbq
               end

               pbq  =
"button[3,4;2,.5;coderskins_page_"  ..
zbpage .. ";Page " .. obpage .. "/" .. nspages .. "]"
               formspec = formspec  .. pbq

               if nspages >= 6 then
                   pba  = math.floor ((nspages * (2/3)) + 0.5)
                   if pba <  1 then pba = 1 end
                   pbx  = tostring (pba)
                   if pba < 10 then pbx = "0"     .. pbx end
                   pbz  = tostring (pba-1) .. ";" .. pbx .. "]"
                   pbq  = "button[5,4;1,.5;coderskins_page_" .. pbz
                   formspec = formspec .. pbq
               end

               if nspages > 3 then
                   if obpage == nspages then
                       pba  = nspages - 1
                       if pba <  1 then pba = 1 end
                   else
                       pba  = nspages
                   end
                   if pba ~= obpage then
                       pbx  = tostring (pba)
                       if pba < 10 then pbx = "0"     .. pbx end
                       pbz  = tostring (pba-1) .. ";" .. pbx .. "]"
                       pbq  = "button[6,4;1,.5;coderskins_page_" .. pbz
                       formspec = formspec .. pbq
                   end
               end
            end

            -- "Next" page button
            if index > 16 then
                formspec = formspec ..
"button[7,4;1,.5;coderskins_page_"  .. (zbpage+1) .. ";>>]"
            else
                formspec = formspec ..
"button[7,4;1,.5;coderskins_page_"  .. zbpage     .. ";>>]"
            end

            return { formspec = formspec }
        end ,
    })
end

-- ===================================================================

minetest.register_on_player_receive_fields (function (player,
formname, fields)

    local plname = player:get_player_name()
    if fields.coderskins then
        unified_inventory.set_inventory_formspec (player, "craft")
    end
    local setpage = false

    for field, _ in pairs (fields) do
        if string.sub (field, 0,
            string.len ("coderskins_page_")) ==
                        "coderskins_page_" then
            local zbpage = tonumber (string.sub (field,
                string.len ("coderskins_page_") + 1))

            coderskins.pages [plname] = zbpage
            unified_inventory.set_inventory_formspec (player,
                "coderskins_page_" .. zbpage)
            setpage = true
        end
    end

    for field, _ in pairs (fields) do
        if string.sub (field, 0,
            string.len ("coderskins_set_")) ==
                        "coderskins_set_" then

            local trbase =
                coderskins.list [tonumber (string.sub (field,
                    string.len ("coderskins_set_") + 1))]

            set_stored_trbase (plname, trbase)
            coderskins.change_skin (plname)

            if setpage == false then
                unified_inventory.set_inventory_formspec (player,
"coderskins")
            end
        end
    end
end)

-- ===================================================================
-- End of file.