local Difficulty = require 'modules.difficulty_vote'

local difficulties_votes = {
    [1] = {amount_modifier = 0.52, strength_modifier = 0.40, boss_modifier = 0.7},
    [2] = {amount_modifier = 0.76, strength_modifier = 0.65, boss_modifier = 0.8},
    [3] = {amount_modifier = 0.92, strength_modifier = 0.85, boss_modifier = 0.9},
    [4] = {amount_modifier = 1.00, strength_modifier = 1.00, boss_modifier = 1.0},
    [5] = {amount_modifier = 1.16, strength_modifier = 1.25, boss_modifier = 1.1},
    [6] = {amount_modifier = 1.48, strength_modifier = 1.75, boss_modifier = 1.2},
    [7] = {amount_modifier = 2.12, strength_modifier = 2.50, boss_modifier = 1.3}
}

function get_biter()
    local max_chance = 0
    for k, v in pairs(global.biter_chances) do
        max_chance = max_chance + v
    end
    local r = math.random(1, max_chance)
    local current_chance = 0
    for k, v in pairs(global.biter_chances) do
        current_chance = current_chance + v
        if r <= current_chance then
            return k
        end
    end
end

function get_worm()
    local max_chance = 0
    for k, v in pairs(global.worm_chances) do
        max_chance = max_chance + v
    end
    local r = math.random(1, max_chance)
    local current_chance = 0
    for k, v in pairs(global.worm_chances) do
        current_chance = current_chance + v
        if r <= current_chance then
            return k
        end
    end
end

function set_biter_chances(level)
    global.biter_chances = {
        ['small-biter'] = 500 - level * 10,
        ['small-spitter'] = 500 - level * 10,
        ['medium-biter'] = level * 10,
        ['medium-spitter'] = level * 10,
        ['big-biter'] = 0,
        ['big-spitter'] = 0,
        ['behemoth-biter'] = 0,
        ['behemoth-spitter'] = 0
    }
    if level > 25 then
        global.biter_chances['big-biter'] = (level - 25) * 25
        global.biter_chances['big-spitter'] = (level - 25) * 25
    end
    if level > 50 then
        global.biter_chances['behemoth-biter'] = (level - 50) * 50
        global.biter_chances['behemoth-spitter'] = (level - 50) * 50
    end
    for k, v in pairs(global.biter_chances) do
        if global.biter_chances[k] < 0 then
            global.biter_chances[k] = 0
        end
    end
end

function set_worm_chances(level)
    global.worm_chances = {
        ['small-worm-turret'] = 500 - level * 10,
        ['medium-worm-turret'] = level * 10,
        ['big-worm-turret'] = 0,
        ['behemoth-worm-turret'] = 0
    }
    if level > 25 then
        global.worm_chances['big-worm-turret'] = (level - 25) * 25
        global.worm_chances['big-worm-turret'] = (level - 25) * 25
    end
    if level > 50 then
        global.worm_chances['behemoth-worm-turret'] = (level - 50) * 50
        global.worm_chances['behemoth-worm-turret'] = (level - 50) * 50
    end
    for k, v in pairs(global.worm_chances) do
        if global.worm_chances[k] < 0 then
            global.worm_chances[k] = 0
        end
    end
end

local function is_boss_stage()
    if global.current_stage == 1 then
        return false
    end
    if global.current_stage == #global.stages - 1 then
        return true
    end
    if #global.stages < 6 then
        return false
    end
    if global.current_stage == math.floor(#global.stages * 0.5) then
        return true
    end
end

function add_enemies(surface, tiles)
    local Diff = Difficulty.get()
    table.shuffle_table(tiles)

    if is_boss_stage() then
        set_biter_chances(
            math.floor((global.current_level * difficulties_votes[Diff.difficulty_vote_index].strength_modifier) + 15)
        )
        local boss_count = math.random(1, math.floor(global.current_level * 0.5) + 1)
        if boss_count > 16 then
            boss_count = 16
        end
        for k, tile in pairs(tiles) do
            if surface.can_place_entity({name = 'small-biter', position = tile.position, force = 'enemy'}) then
                local unit = surface.create_entity({name = get_biter(), position = tile.position, force = 'enemy'})
                unit.ai_settings.allow_destroy_when_commands_fail = false
                unit.ai_settings.allow_try_return_to_spawner = false
                add_boss_unit(
                    unit,
                    (3 + global.current_level * 0.2) * difficulties_votes[Diff.difficulty_vote_index].boss_modifier,
                    0.55
                )
                global.alive_boss_enemy_count = global.alive_boss_enemy_count + 1
                global.alive_boss_enemy_entities[unit.unit_number] = unit
                global.alive_enemies = global.alive_enemies + 1
                boss_count = boss_count - 1
                if boss_count == 0 then
                    break
                end
            end
        end
    end

    if global.current_level > 2 then
        if math.random(1, 5) == 1 or is_boss_stage() then
            local evolution =
                (global.current_level * 2 * difficulties_votes[Diff.difficulty_vote_index].strength_modifier) * 0.01
            if evolution > 1 then
                evolution = 1
            end
            game.forces.enemy_spawners.evolution_factor = evolution
            local count = math.random(1, math.ceil(global.current_level * 0.10))
            if count > 5 then
                count = 5
            end
            for k, tile in pairs(tiles) do
                if
                    surface.can_place_entity(
                        {name = 'biter-spawner', position = tile.position, force = 'enemy_spawners'}
                    )
                 then
                    surface.create_entity({name = 'biter-spawner', position = tile.position, force = 'enemy_spawners'})
                    global.alive_enemies = global.alive_enemies + 1
                    count = count - 1
                    if count == 0 then
                        break
                    end
                end
            end
        end
    end

    if math.random(1, 4) == 1 or is_boss_stage() then
        set_worm_chances(global.current_level)
        local worm_count = math.random(1, math.ceil(global.current_level * 0.5))
        if worm_count > 32 then
            worm_count = 32
        end
        for k, tile in pairs(tiles) do
            if surface.can_place_entity({name = 'big-worm-turret', position = tile.position, force = 'enemy'}) then
                surface.create_entity({name = get_worm(), position = tile.position, force = 'enemy'})
                global.alive_enemies = global.alive_enemies + 1
                worm_count = worm_count - 1
                if worm_count == 0 then
                    break
                end
            end
        end
    end

    set_biter_chances(
        math.floor(global.current_level * difficulties_votes[Diff.difficulty_vote_index].strength_modifier) + 1
    )
    local amount = ((global.current_level * 25) / #global.stages) * global.current_stage
    amount = amount * difficulties_votes[Diff.difficulty_vote_index].amount_modifier
    for k, tile in pairs(tiles) do
        if surface.can_place_entity({name = 'small-biter', position = tile.position, force = 'enemy'}) then
            local unit = surface.create_entity({name = get_biter(), position = tile.position, force = 'enemy'})
            unit.ai_settings.allow_destroy_when_commands_fail = false
            unit.ai_settings.allow_try_return_to_spawner = false
            global.alive_enemies = global.alive_enemies + 1
            amount = amount - 1
        end
        if amount <= 0 then
            break
        end
    end

    update_stage_gui()
end