-- Functions

local function build_portal (pos, target)
    local p1 = {x = pos.x - 1, y = pos.y - 1, z = pos.z}
    local p2 = {x = p1.x + 3, y = p1.y + 4, z = p1.z}

    local path = minetest.get_modpath("nether") .. "/schematics/nether_portal.mts"
    minetest.place_schematic({x = p1.x, y = p1.y, z = p1.z - 2}, path, 0, nil, true)

    for y = p1.y, p2.y do
    for x = p1.x, p2.x do
        local meta = minetest.get_meta({x = x, y = y, z = p1.z})
        meta:set_string("p1", minetest.pos_to_string(p1))
        meta:set_string("p2", minetest.pos_to_string(p2))
        meta:set_string("target", minetest.pos_to_string(target))
    end
    end
end

local function move_check(p1, max, dir)
    local p = {x = p1.x, y = p1.y, z = p1.z}
    local d = math.abs(max - p1[dir]) / (max - p1[dir])

    while p[dir] ~= max do
        p[dir] = p[dir] + d
        if minetest.get_node(p).name ~= "default:obsidian" then
            return false
        end
    end

    return true
end

local function check_portal(p1, p2)
    if p1.x ~= p2.x then
        if not move_check(p1, p2.x, "x") then
            return false
        end
        if not move_check(p2, p1.x, "x") then
            return false
        end
    elseif p1.z ~= p2.z then
        if not move_check(p1, p2.z, "z") then
            return false
        end
        if not move_check(p2, p1.z, "z") then
            return false
        end
    else
        return false
    end

    if not move_check(p1, p2.y, "y") then
        return false
    end
    if not move_check(p2, p1.y, "y") then
        return false
    end

    return true
end

local function is_portal(pos)
    for d = -3, 3 do
        for y = -4, 4 do
            local px = {x = pos.x + d, y = pos.y + y, z = pos.z}
            local pz = {x = pos.x, y = pos.y + y, z = pos.z + d}

            if check_portal(px, {x = px.x + 3, y = px.y + 4, z = px.z}) then
                return px, {x = px.x + 3, y = px.y + 4, z = px.z}
            end
            if check_portal(pz, {x = pz.x, y = pz.y + 4, z = pz.z + 3}) then
                return pz, {x = pz.x, y = pz.y + 4, z = pz.z + 3}
            end
        end
    end
end

local function make_portal(pos)
    local p1, p2 = is_portal(pos)
    if not p1 or not p2 then
        return false
    end

    for d = 1, 2 do
    for y = p1.y + 1, p2.y - 1 do
        local p
        if p1.z == p2.z then
            p = {x = p1.x + d, y = y, z = p1.z}
        else
            p = {x = p1.x, y = y, z = p1.z + d}
        end
        if minetest.get_node(p).name ~= "air" then
            return false
        end
    end
    end

    local param2
    if p1.z == p2.z then
        param2 = 0
    else
        param2 = 1
    end

    local target = {x = p1.x, y = p1.y, z = p1.z}
    -- don't find nether, since nether-blocks not nether mod

    for d = 0, 3 do
    for y = p1.y, p2.y do
        local p
        if param2 == 0 then
            p = {x = p1.x + d, y = y, z = p1.z}
        else
            p = {x = p1.x, y = y, z = p1.z + d}
        end
        if minetest.get_node(p).name == "air" then
            minetest.set_node(p, {name = "nether:portal", param2 = param2})
        end
        local meta = minetest.get_meta(p)
        meta:set_string("p1", minetest.pos_to_string(p1))
        meta:set_string("p2", minetest.pos_to_string(p2))
        meta:set_string("target", minetest.pos_to_string(target))
    end
    end

    return true
end

-- ABMs

minetest.register_abm({
    nodenames = {"nether:portal"},
    interval = 1,
    chance = 2,
    action = function(pos, node)
        minetest.add_particlespawner({
            32, --amount
            4, --time
            {x = pos.x - 0.25, y = pos.y - 0.25, z = pos.z - 0.25}, --minpos
            {x = pos.x + 0.25, y = pos.y + 0.25, z = pos.z + 0.25}, --maxpos
            {x = -0.8, y = -0.8, z = -0.8}, --minvel
            {x = 0.8, y = 0.8, z = 0.8}, --maxvel
            {x = 0, y = 0, z = 0}, --minacc
            {x = 0, y = 0, z = 0}, --maxacc
            0.5, --minexptime
            1, --maxexptime
            1, --minsize
            2, --maxsize
            false, --collisiondetection
            "nether_particle.png" --texture
        })
    end,
})

minetest.register_node(":default:obsidian", {
    description = "Obsidian",
    tiles = {"default_obsidian.png"},
    is_ground_content = false,
    sounds = default.node_sound_stone_defaults(),
    groups = {cracky = 1, level = 2},

    on_destruct = function(pos)
        local meta = minetest.get_meta(pos)
        local p1 = minetest.string_to_pos(meta:get_string("p1"))
        local p2 = minetest.string_to_pos(meta:get_string("p2"))
        local target = minetest.string_to_pos(meta:get_string("target"))
        if not p1 or not p2 then
            return
        end

        for x = p1.x, p2.x do
        for y = p1.y, p2.y do
        for z = p1.z, p2.z do
            local nn = minetest.get_node({x = x, y = y, z = z}).name
            if nn == "default:obsidian" or nn == "nether:portal" then
                if nn == "nether:portal" then
                    minetest.remove_node({x = x, y = y, z = z})
                end
                local m = minetest.get_meta({x = x, y = y, z = z})
                m:set_string("p1", "")
                m:set_string("p2", "")
                m:set_string("target", "")
            end
        end
        end
        end

        meta = minetest.get_meta(target)
        if not meta then
            return
        end
        p1 = minetest.string_to_pos(meta:get_string("p1"))
        p2 = minetest.string_to_pos(meta:get_string("p2"))
        if not p1 or not p2 then
            return
        end

        for x = p1.x, p2.x do
        for y = p1.y, p2.y do
        for z = p1.z, p2.z do
            local nn = minetest.get_node({x = x, y = y, z = z}).name
            if nn == "default:obsidian" or nn == "nether:portal" then
                if nn == "nether:portal" then
                    minetest.remove_node({x = x, y = y, z = z})
                end
                local m = minetest.get_meta({x = x, y = y, z = z})
                m:set_string("p1", "")
                m:set_string("p2", "")
                m:set_string("target", "")
            end
        end
        end
        end
    end,
})

-- Craftitems

minetest.override_item("default:mese_crystal_fragment", {
    on_place = function(stack, _, pt)
        if pt.under and minetest.get_node(pt.under).name == "default:obsidian" then
            local done = make_portal(pt.under)
            if done and not minetest.settings:get_bool("creative_mode") then
                stack:take_item()
            end
        end

        return stack
    end,
})