require("game")

function love.load()

    -- the level data is a matrix!
    -- limitation: there MUST be walls limiting the level
    levels = {
        {
            { '#', '#', '#', '#', '#', '#', '#' },
            { '#', '.', '@', ' ', '#', ' ', '#' },
            { '#', '$', '*', ' ', '$', ' ', '#' },
            { '#', ' ', ' ', ' ', '$', ' ', '#' },
            { '#', ' ', '.', '.', ' ', ' ', '#' },
            { '#', ' ', ' ', '*', ' ', ' ', '#' },
            { '#', '#', '#', '#', '#', '#', '#' }
        },
        {
            { '#','#','#','#','#','#',' ',' '},
            { '#',' ',' ',' ',' ','#','#','#'},
            { '#',' ','#',' ','$',' ',' ','#'},
            { '#','.','.','.','*','$','@','#'},
            { '#',' ','#',' ','$',' ',' ','#'},
            { '#',' ',' ',' ','#','#','#','#'},
            { '#','#','#','#','#',' ',' ',' '}
        }
    }

    -- use a monospaced font (TODO: licence)
    font = love.graphics.newFont("data/Monocraft.otf", 12 * game.scale)

    -- load graphics
    ground = love.graphics.newImage("data/ground.png")
    crate = love.graphics.newImage("data/crate.png")
    wall = love.graphics.newImage("data/wall.png")
    goal = love.graphics.newImage("data/goal.png")
    crate_goal = love.graphics.newImage("data/crate_goal.png")

    player_frames = {
        love.graphics.newImage("data/player_01.png"),
        love.graphics.newImage("data/player_02.png")
    }
    player_frame = 1
    player_delay = 0

    -- where the player is
    player_x = 0
    player_y = 0
    moves = 0

    state = "play"
    current_level = 1
    set_level(current_level)
end

-- return true if all the crates are in storage
function is_level_complete()
    for _, row in ipairs(level) do
        for _, cell in ipairs(row) do
            if cell == '$' then
                return false
            end
        end
    end
    return true
end

-- set current level based on the index in the levels table
function set_level(number)
    level_undo = {}
    level_undo_x = 0
    level_undo_y = 0

    level = {}
    for y, row in ipairs(levels[number]) do
        level[y] = {}
        for x, cell in ipairs(row) do
            level[y][x] = cell
            if cell == '@' or cell == '+' then
                player_x = x
                player_y = y
            end
        end
    end
    moves = 0
end

-- perform a move (if possible)
function move(target_x, target_y)
    -- can't push walls
    if level[player_y + target_y][player_x + target_x] == '#' then
        return
    end

    local current = level[player_y][player_x]
    local destination = level[player_y + target_y][player_x + target_x]

    -- copy current level and player position to use it for undo
    local undo = {}
    local undo_x = 0
    local undo_y = 0
    for y, row in ipairs(level) do
        undo[y] = {}
        for x, cell in ipairs(row) do
            undo[y][x] = cell
            if cell == '@' or cell == '+' then
                undo_x = x
                undo_y = y
            end
        end
    end

    -- pushing a box
    if destination == '$' or destination == '*' then
        local destination_crate = level[player_y + target_y * 2][player_x + target_x * 2]
        -- can we move it?
        if destination_crate == ' ' or destination_crate == '.' then
            -- first erase the current position
            if destination == '$' then
                level[player_y + target_y][player_x + target_x] = ' '
                destination = ' '
            else
                level[player_y + target_y][player_x + target_x] = '.'
                destination = '.'
            end

            -- second draw on the new one
            if destination_crate == ' ' then
                level[player_y + target_y * 2][player_x + target_x * 2] = '$'
            else
                level[player_y + target_y * 2][player_x + target_x * 2] = '*'
            end
        else
            -- we can't, so we don't move
            return
        end
    end

    -- first erase the current position
    if current == '@' then
        level[player_y][player_x] = ' '
    else
        level[player_y][player_x] = '.'
    end

    -- second draw on the new one
    if destination == ' ' then
        level[player_y + target_y][player_x + target_x] = '@'
    else
        level[player_y + target_y][player_x + target_x] = '+'
    end

    player_x = player_x + target_x
    player_y = player_y + target_y
    moves = moves + 1

    -- save the previous move for UNDO
    level_undo = undo
    level_undo_x = undo_x
    level_undo_y = undo_y
end

-- keypressed handler when the level is compplete
function keypressed_win(key)
    if key == "space" then
        -- loop if we run out of levels
        if current_level == #levels then
            current_level = 1
        else
            current_level = current_level + 1
        end
        -- back to play!
        set_level(current_level)
        state = "play"
    end
end

-- keypressed handler during play
function keypressed_play(key)
    if key == "r" then
        -- reset level
        set_level(current_level)
        return
    elseif key == "u" and #level_undo > 0 then
        -- undo move
        level = level_undo
        player_x = level_undo_x
        player_y = level_undo_y
        level_undo = {}
        moves = moves - 1
    end

    -- where are we moving
    local target_x = 0
    local target_y = 0

    if key == "up" then
        target_y = -1
    elseif key == "down" then
        target_y = 1
    elseif key == "left" then
        target_x = -1
    elseif key=="right" then
        target_x = 1
    end

    -- only if we move
    if target_x ~= 0 or target_y ~= 0 then
        move(target_x, target_y)

        if is_level_complete() then
            win_delay = 0
            state = "win"
        end
    end
end

function love.keypressed(key)

    -- quit game
    if key == "escape" then
        print("bye bye!")
        love.event.quit()
    end

    if state == "play"  then
        keypressed_play(key)
    elseif state == "win" then
        keypressed_win(key)
    end
end

function love.update(dt)
    player_delay = player_delay + dt * 3
    if player_delay > 1 then
        player_delay = 0
        if player_frame == 1 then
            player_frame = 2
        else
            player_frame = 1
        end
    end
end

function love.draw()

    love.graphics.setFont(font)

    love.graphics.print("Level " .. current_level .. "  Moves " .. moves, 20, 5 * game.scale)

    -- these options anly exist when we are playing
    if state == "play" then
        love.graphics.print("R:restart", 20, 205 * game.scale)

        -- change colour if there's not undo
        if #level_undo == 0 then
            love.graphics.setColor(0.5, 0.3, 0.3)
        end
        love.graphics.print("U:undo", 20 + 10 * 8 * game.scale, 205 * game.scale)
        love.graphics.setColor(1, 1, 1)

        love.graphics.print("ESC:exit", 20 + 17 * 8 * game.scale, 205 * game.scale)
    end

    love.graphics.print("Storage Chaos", 20, 220 * game.scale)

    for y, row in ipairs(level) do
        for x, cell in ipairs(row) do
            -- for testing
            -- love.graphics.print(cell, 10 + x * 12 * game.scale, 10 + y * 12 * game.scale)

            draw_x = 10 + x * 64
            draw_y = 10 + y * 64

            -- always draw the ground
            love.graphics.draw(ground, draw_x, draw_y)
            if cell == '#' then
                love.graphics.draw(wall, draw_x, draw_y)
            elseif cell == '$' then
                love.graphics.draw(crate, draw_x, draw_y)
            elseif cell == '.' then
                love.graphics.draw(goal, draw_x, draw_y)
            elseif cell == '*' then
                love.graphics.draw(crate_goal, draw_x, draw_y)
            end

            if cell == '@' then
                love.graphics.draw(player_frames[player_frame], draw_x, draw_y)
            elseif cell == '+' then
                love.graphics.draw(goal, draw_x, draw_y)
                love.graphics.draw(player_frames[player_frame], draw_x, draw_y)
            end
        end
    end

    -- if the level is completed, show an verlay
    if state == "win" then
        if win_delay < 64 then
            win_delay = win_delay + 1
        else
            love.graphics.setColor(0.3, 0.3, 0.5)
            love.graphics.rectangle("fill", 0, 80 * game.scale, game.width * game.scale, 60 * game.scale)
            love.graphics.setColor(1.0, 1.0, 1.0)
            love.graphics.print("Level completed!", 96 * game.scale, 90 * game.scale)
            love.graphics.print("SPACE:next  ESC:quit", 80 * game.scale, 115 * game.scale)
        end
    end
end

function love.keyreleased(key)
end