--luacheck: ignore
local Public = {}
local simplex_noise = require 'utils.simplex_noise'.d2
local math_random = math.random
local math_abs = math.abs
local math_sqrt = math.sqrt
local math_floor = math.floor
local table_remove = table.remove
local table_insert = table.insert
local table_shuffle_table = table.shuffle_table
local chart_radius = 30
local start_chunk_y = 5
local tile_conversion = {
    ['concrete'] = 'stone-path',
    ['hazard-concrete-left'] = 'stone-path',
    ['hazard-concrete-right'] = 'stone-path',
    ['refined-concrete'] = 'concrete',
    ['refined-hazard-concrete-left'] = 'hazard-concrete-left',
    ['refined-hazard-concrete-right'] = 'hazard-concrete-right',
    ['stone-path'] = 'landfill'
}

local size_of_vector_list = 64
local function get_collapse_vectors(radius, seed)
    local vectors = {}
    local i = 1
    local m = 1 / (radius * 2)
    for x = radius * -1, radius, 1 do
        for y = radius * -1, radius, 1 do
            local noise = math_abs(simplex_noise(x * m, y * m, seed) * radius * 1.2)
            local d = math_sqrt(x ^ 2 + y ^ 2)
            if d + noise < radius then
                vectors[i] = {x, y}
                i = i + 1
            end
        end
    end

    local sorted_vectors = {}
    for _, vector in pairs(vectors) do
        local index = math_floor(math_sqrt(vector[1] ^ 2 + vector[2] ^ 2)) + 1
        if not sorted_vectors[index] then
            sorted_vectors[index] = {}
        end
        sorted_vectors[index][#sorted_vectors[index] + 1] = vector
    end

    local final_list = {}
    for _, row in pairs(sorted_vectors) do
        table_shuffle_table(row)
        for _, tile in pairs(row) do
            table_insert(final_list, tile)
        end
    end

    return final_list
end

local function set_y(surface)
    local level_width = surface.map_gen_settings.width
    local map_collapse = global.map_collapse
    local x_left = surface.map_gen_settings.width * -0.5
    local x_right = surface.map_gen_settings.width * 0.5
    for _ = 1, 16, 1 do
        local area = {{x_left, map_collapse.last_position.y}, {x_right, map_collapse.last_position.y + 1}}
        if surface.count_tiles_filtered({name = 'out-of-map', area = area}) < level_width then
            return area
        end
        map_collapse.last_position.y = map_collapse.last_position.y - 1
    end
end

local function set_positions(surface)
    local area = set_y(surface)
    if not area then
        return
    end

    local map_collapse = global.map_collapse
    map_collapse.positions = {}

    local i = 1
    for _, tile in pairs(surface.find_tiles_filtered({area = area})) do
        if tile.valid then
            if tile.name ~= 'out-of-map' then
                map_collapse.positions[i] = tile
                i = i + 1
            end
        end
    end

    if i == 1 then
        map_collapse.positions = nil
        return
    end
    if i > 1 then
        table_shuffle_table(map_collapse.positions)
    end
end

local function set_collapse_tiles(surface, position, vectors)
    local map_collapse = global.map_collapse
    map_collapse.processing = {}
    local i = 1
    for _, vector in pairs(vectors) do
        local shifted_position = {x = position[1] + vector[1], y = position[2] + vector[2] - 60}
        local position = {x = position[1] + vector[1], y = position[2] + vector[2]}
        local rocks = surface.find_entities_filtered {position = shifted_position, radius = 2, type = {'simple-entity', 'tree'}}
        if #rocks > 0 then
            for i = 1, #rocks, 1 do
                if rocks[i].valid then
                    rocks[i].destroy()
                end
            end
        end
        local tile = surface.get_tile(position)
        if tile.valid and tile.name ~= 'out-of-map' then
            map_collapse.processing[i] = tile
            i = i + 1
        end
    end
    map_collapse.processing_index = 1
    map_collapse.size_of_processing = #map_collapse.processing
end

local function clean_positions(tbl)
    for k, tile in pairs(tbl) do
        if not tile.valid then
            table_remove(tbl, k)
        else
            if tile.name == 'out-of-map' then
                table_remove(tbl, k)
            end
        end
    end
end

local function setup_next_collapse()
    local surface = game.surfaces[global.active_surface_index]
    local map_collapse = global.map_collapse
    if not map_collapse.vector_list then
        map_collapse.vector_list = {}
        for _ = 1, size_of_vector_list, 1 do
            table_insert(global.map_collapse.vector_list, get_collapse_vectors(math_random(24, 48), math_random(1, 9999999)))
        end
    end

    if not map_collapse.positions then
        --if math_random(1, 64) == 1 then map_collapse.last_position = {x = 0, y = 128} end
        set_positions(surface)
        return
    end

    local tile = map_collapse.positions[#map_collapse.positions]
    if not tile then
        map_collapse.positions = nil
        return
    end
    if not tile.valid then
        clean_positions(map_collapse.positions)
        return
    end
    if tile.name == 'out-of-map' then
        clean_positions(map_collapse.positions)
        return
    end

    local position = {tile.position.x, tile.position.y}

    local vectors = map_collapse.vector_list[math_random(1, size_of_vector_list)]
    set_collapse_tiles(surface, position, vectors)

    local last_position = global.map_collapse.last_position
    game.forces.player.chart(surface, {{last_position.x - chart_radius, last_position.y - chart_radius}, {last_position.x + chart_radius, last_position.y + chart_radius}})
    global.map_collapse.last_position = {x = position[1], y = position[2]}
    game.forces.player.chart(surface, {{position[1] - chart_radius, position[2] - chart_radius}, {position[1] + chart_radius, position[2] + chart_radius}})
end

function Public.delete_out_of_map_chunks(surface)
    local count = 0
    for chunk in surface.get_chunks() do
        if surface.count_tiles_filtered({name = 'out-of-map', area = chunk.area}) == 1024 then
            surface.delete_chunk({chunk.x, chunk.y})
            count = count + 1
        end
    end
end

local function process_tile(surface, tile, tiles_to_set)
    if not tile then
        return
    end
    if not tile.valid then
        return
    end

    local conversion_tile = tile_conversion[tile.name]
    if conversion_tile then
        table_insert(tiles_to_set, {name = conversion_tile, position = tile.position})
        surface.create_trivial_smoke({name = 'train-smoke', position = tile.position})
    else
        table_insert(tiles_to_set, {name = 'out-of-map', position = tile.position})
    end

    return true
end

function Public.process()
    local surface = game.surfaces[global.active_surface_index]
    local map_collapse = global.map_collapse

    if map_collapse.processing_index >= map_collapse.size_of_processing then
        setup_next_collapse()
        return
    end

    local count = 0
    local tiles_to_set = {}
    for i = map_collapse.processing_index, map_collapse.size_of_processing, 1 do
        if process_tile(surface, map_collapse.processing[i], tiles_to_set) then
            count = count + 1
            if count >= map_collapse.speed then
                break
            end
        end
        map_collapse.processing_index = map_collapse.processing_index + 1
    end

    if count > 1 then
        surface.set_tiles(tiles_to_set, true)
    end
end

function Public.init()
    global.map_collapse = {
        ['processing_index'] = 0,
        ['size_of_processing'] = 0,
        ['processing'] = {},
        ['last_position'] = {x = 0, y = 128},
        ['speed'] = 3
    }
end

local event = require 'utils.event'
event.on_init(Public.init())

return Public
