local anim8 = {
    _VERSION     = 'anim8 v2.3.1',
    _DESCRIPTION = 'An animation library for LÖVE',
    _URL         = 'https://github.com/kikito/anim8',
    _LICENSE     = [[
    MIT LICENSE

    Copyright (c) 2011 Enrique García Cota

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
    OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  ]]
}

local Grid = {}

local _frames = {}

local function assertPositiveInteger(value, name)
    if type(value) ~= 'number' then error(("%s should be a number, was %q"):format(name, tostring(value))) end
    if value < 1 then error(("%s should be a positive number, was %d"):format(name, value)) end
    if value ~= math.floor(value) then error(("%s should be an integer, was %f"):format(name, value)) end
end

local function createFrame(self, x, y)
    local fw, fh = self.frameWidth, self.frameHeight
    return love.graphics.newQuad(
        self.left + (x - 1) * fw + x * self.border,
        self.top + (y - 1) * fh + y * self.border,
        fw,
        fh,
        self.imageWidth,
        self.imageHeight
    )
end

local function getGridKey(...)
    return table.concat({ ... }, '-')
end

local function getOrCreateFrame(self, x, y)
    if x < 1 or x > self.width or y < 1 or y > self.height then
        error(("There is no frame for x=%d, y=%d"):format(x, y))
    end
    local key          = self._key
    _frames[key]       = _frames[key] or {}
    _frames[key][x]    = _frames[key][x] or {}
    _frames[key][x][y] = _frames[key][x][y] or createFrame(self, x, y)
    return _frames[key][x][y]
end

local function parseInterval(str)
    if type(str) == "number" then return str, str, 1 end
    str = str:gsub('%s', '') -- remove spaces
    local min, max = str:match("^(%d+)-(%d+)$")
    assert(min and max, ("Could not parse interval from %q"):format(str))
    min, max = tonumber(min), tonumber(max)
    local step = min <= max and 1 or -1
    return min, max, step
end

function Grid:getFrames(...)
    local result, args = {}, { ... }
    local minx, maxx, stepx, miny, maxy, stepy

    for i = 1, #args, 2 do
        minx, maxx, stepx = parseInterval(args[i])
        miny, maxy, stepy = parseInterval(args[i + 1])
        for y = miny, maxy, stepy do
            for x = minx, maxx, stepx do
                result[#result + 1] = getOrCreateFrame(self, x, y)
            end
        end
    end

    return result
end

local Gridmt = {
    __index = Grid,
    __call  = Grid.getFrames
}

local function newGrid(frameWidth, frameHeight, imageWidth, imageHeight, left, top, border)
    assertPositiveInteger(frameWidth, "frameWidth")
    assertPositiveInteger(frameHeight, "frameHeight")
    assertPositiveInteger(imageWidth, "imageWidth")
    assertPositiveInteger(imageHeight, "imageHeight")

    left       = left or 0
    top        = top or 0
    border     = border or 0

    local key  = getGridKey(frameWidth, frameHeight, imageWidth, imageHeight, left, top, border)

    local grid = setmetatable(
        {
            frameWidth  = frameWidth,
            frameHeight = frameHeight,
            imageWidth  = imageWidth,
            imageHeight = imageHeight,
            left        = left,
            top         = top,
            border      = border,
            width       = math.floor(imageWidth / frameWidth),
            height      = math.floor(imageHeight / frameHeight),
            _key        = key
        },
        Gridmt
    )
    return grid
end

-----------------------------------------------------------

local Animation = {}

local function cloneArray(arr)
    local result = {}
    for i = 1, #arr do result[i] = arr[i] end
    return result
end

local function parseDurations(durations, frameCount)
    local result = {}
    if type(durations) == 'number' then
        for i = 1, frameCount do result[i] = durations end
    else
        local min, max, step
        for key, duration in pairs(durations) do
            assert(type(duration) == 'number', "The value [" .. tostring(duration) .. "] should be a number")
            min, max, step = parseInterval(key)
            for i = min, max, step do result[i] = duration end
        end
    end

    if #result < frameCount then
        error("The durations table has length of " ..
        tostring(#result) .. ", but it should be >= " .. tostring(frameCount))
    end

    return result
end

local function parseIntervals(durations)
    local result, time = { 0 }, 0
    for i = 1, #durations do
        time = time + durations[i]
        result[i + 1] = time
    end
    return result, time
end

local Animationmt = { __index = Animation }
local nop = function() end

local function newAnimation(frames, durations, onLoop)
    local td = type(durations);
    if (td ~= 'number' or durations <= 0) and td ~= 'table' then
        error("durations must be a positive number. Was " .. tostring(durations))
    end
    onLoop = onLoop or nop
    durations = parseDurations(durations, #frames)
    local intervals, totalDuration = parseIntervals(durations)
    return setmetatable({
            frames        = cloneArray(frames),
            durations     = durations,
            intervals     = intervals,
            totalDuration = totalDuration,
            onLoop        = onLoop,
            timer         = 0,
            position      = 1,
            status        = "playing",
            flippedH      = false,
            flippedV      = false
        },
        Animationmt
    )
end

function Animation:clone()
    local newAnim = newAnimation(self.frames, self.durations, self.onLoop)
    newAnim.flippedH, newAnim.flippedV = self.flippedH, self.flippedV
    return newAnim
end

function Animation:flipH()
    self.flippedH = not self.flippedH
    return self
end

function Animation:flipV()
    self.flippedV = not self.flippedV
    return self
end

local function seekFrameIndex(intervals, timer)
    local high, low, i = #intervals - 1, 1, 1

    while (low <= high) do
        i = math.floor((low + high) / 2)
        if timer >= intervals[i + 1] then
            low = i + 1
        elseif timer < intervals[i] then
            high = i - 1
        else
            return i
        end
    end

    return i
end

function Animation:update(dt)
    if self.status ~= "playing" then return end

    self.timer = self.timer + dt
    local loops = math.floor(self.timer / self.totalDuration)
    if loops ~= 0 then
        self.timer = self.timer - self.totalDuration * loops
        local f = type(self.onLoop) == 'function' and self.onLoop or self[self.onLoop]
        f(self, loops)
    end

    self.position = seekFrameIndex(self.intervals, self.timer)
end

function Animation:pause()
    self.status = "paused"
end

function Animation:gotoFrame(position)
    self.position = position
    self.timer = self.intervals[self.position]
end

function Animation:pauseAtEnd()
    self.position = #self.frames
    self.timer = self.totalDuration
    self:pause()
end

function Animation:pauseAtStart()
    self.position = 1
    self.timer = 0
    self:pause()
end

function Animation:resume()
    self.status = "playing"
end

function Animation:draw(image, x, y, r, sx, sy, ox, oy, kx, ky)
    love.graphics.draw(image, self:getFrameInfo(x, y, r, sx, sy, ox, oy, kx, ky))
end

function Animation:getFrameInfo(x, y, r, sx, sy, ox, oy, kx, ky)
    local frame = self.frames[self.position]
    if self.flippedH or self.flippedV then
        r, sx, sy, ox, oy, kx, ky = r or 0, sx or 1, sy or 1, ox or 0, oy or 0, kx or 0, ky or 0
        local _, _, w, h = frame:getViewport()

        if self.flippedH then
            sx = sx * -1
            ox = w - ox
            kx = kx * -1
            ky = ky * -1
        end

        if self.flippedV then
            sy = sy * -1
            oy = h - oy
            kx = kx * -1
            ky = ky * -1
        end
    end
    return frame, x, y, r, sx, sy, ox, oy, kx, ky
end

function Animation:getDimensions()
    local _, _, w, h = self.frames[self.position]:getViewport()
    return w, h
end

-----------------------------------------------------------

anim8.newGrid      = newGrid
anim8.newAnimation = newAnimation

return anim8
