--- The Pop.Box GUI itself.
--- @module pop
--- @copyright Paul Liverman III (2015-2016)
--- @license The MIT License (MIT)
--- @release 0.0.0

pop = {
    _VERSION: '0.0.0'
    _DESCRIPTION: 'GUI library for LOVE, designed for ease of use'
    _URL: 'http://github.com/Guard13007/Pop.Box'
    _LICENSE: 'The MIT License (MIT)'
    _AUTHOR: 'Paul Liverman III'
}

log = (...) ->
    print "[Pop.Box]", ...

unless love.getVersion
    error "Pop.Box only supports LOVE versions >= 0.9.1"

path = (...)\gsub "%.", "/"

if (...)\sub(-4) == "init"
    path = (...)\sub 1, -5
    unless path
        path = "."

log "Require path detected: \"#{path}\""

import filesystem, graphics from love
import insert from table
import inheritsFromElement from require "#{path}/util"

--- @table pop
--- @tfield table elements All GUI classes are stored here.
--- @tfield table skins All skins are stored here.
--- @tfield table extensions All extensions are loaded here.
--- @tfield Element screen The top level GUI element. Represents the game
--- screen. Initialized in `pop.load()`
--- @tfield ?Element|false focused The currently focused GUI element (or `false`
--- if none is focused).
--- @see pop.load
--- @see Element

pop.elements = {}
pop.skins = {}
pop.extensions = {}
pop.screen = false
pop.focused = false
pop.log = log



--- Loads elements, skins, extensions, and initializes `pop.screen`.
---
--- **IMPORTANT**: Intended to only be called once, and is automatically called
--- when you require Pop.Box.
--- @function load
--- @see pop
--- @see Element

pop.load = ->
    --@todo @ see Skins
    --@todo @ see Extensions
    log "Loading elements from \"#{path}/elements\""
    elements = filesystem.getDirectoryItems "#{path}/elements"
    for i = 1, #elements
        -- ignore non-Lua files
        unless elements[i]\sub(-4) == ".lua"
            log "Ignored non-Lua file \"#{path}/elements/#{elements[i]}\""
            continue

        -- require into pop.elements table by filename
        name = elements[i]\sub 1, -5
        log "Requiring \"#{name}\" from \"#{path}/elements/#{name}\""
        pop.elements[name] = require "#{path}/elements/#{name}"

        -- call the element's load function if it exists
        if pop.elements[name].load
            pop.elements[name].load pop

        log "Element loaded: \"#{name}\""

        -- create "pop.element()" function wrapper if possible
        unless pop[name]
            if pop.elements[name].wrap
                pop[name] = pop.elements[name].wrap pop
            else
                pop[name] = (...) ->
                    return pop.create(name, ...)

            log "Wrapper created: \"pop.#{name}()\""


    skins = filesystem.getDirectoryItems "#{path}/skins"
    for i = 1, #skins
        -- ignore non-Lua files
        unless skins[i]\sub(-4) == ".lua"
            log "Ignored non-Lua file \"#{path}/skins/#{skins[i]}\""
            continue

        -- require into pop.skins table by filename
        name = skins[i]\sub 1, -5
        log "Requiring \"#{name}\" from \"#{path}/skins/#{name}\""
        pop.skins[name] = require "#{path}/skins/#{name}"

        -- call the skin's load function if it exists
        if pop.skins[name].load
            pop.skins[name].load pop

        log "Skin loaded: \"#{name}\""


    extensions = filesystem.getDirectoryItems "#{path}/extensions"
    for i = 1, #extensions
        -- ignore non-Lua files
        unless extensions[i]\sub(-4) == ".lua"
            log "Ignored non-Lua file \"#{path}/extensions/#{extensions[i]}\""
            continue

        -- require into pop.extensions by filename
        name = extensions[i]\sub 1, -5
        log "Requiring \"#{name}\" from \"#{path}/extensions/#{name}\""
        pop.extensions[name] = require "#{path}/extensions/#{name}"

        -- call the extension's load function if it exists
        if pop.extensions[name].load
            pop.extensions[name].load pop

        log "Extension loaded: \"#{name}\""


    -- Initialize pop.screen (top element, GUI area)
    pop.screen = pop.create("element", false)\setSize(graphics.getWidth!, graphics.getHeight!)
    log "Created \"pop.screen\""



--- Creates an element.
--- @function create
--- @tparam string element The element class to use.
--- @tparam ?Element|false|nil parent[opt] The parent element. If `false`, an
--- element is created with no parent. If `nil`, defaults to `pop.screen`.
--- @param ...[opt] Any number of parameters can be passed to the constructor
--- for the element.
---
--- (**Note**: An element with no parent will not be handled by Pop.Box's event
--- handlers unless you handle it explicitly.)
--- @see pop
--- @see Element

pop.create = (element, parent=pop.screen, ...) ->
    -- if valid parent element, use it
    if inheritsFromElement parent
        element = pop.elements[element](parent, ...)
        insert parent.child, element
        insert parent.data.child, element.data
        element.parent = parent --this should already have been set by the element, this is here as a precaution
        element.data.parent = parent.data
    -- if explicitly no parent, just create the element
    elseif parent == false
        element = pop.elements[element](false, ...)
        element.parent = false
        element.data.parent = false
    -- else use pop.screen (and "parent" is actually the first argument)
    else
        element = pop.elements[element](pop.screen, parent, ...)
        insert pop.screen.child, element
        insert pop.screen.data.child, element.data
        element.parent = pop.screen --this should already have been set by the element, this is here as a precaution
        element.data.parent = pop.screen.data

    return element



--- Event handler for `love.update()`.
--- @function update
--- @tparam number dt The amount of time passed since the last call to update,
--- in seconds.
--- @tparam Element element[opt] The element to update (will update all its
--- children as well). Defaults to `pop.screen`.
--- @see Element

pop.update = (dt, element=pop.screen) ->
    --- @todo Define Elements and @ see that documentation from here. Generic documentation, not specifically element!
    -- data.update boolean controls an element and its children being updated
    if element.data.update
        if element.update
            element\update dt
        for i = 1, #element.child
            pop.update dt, element.child[i]



--- Event handler for `love.draw()`.
--- @function draw
--- @tparam Element element[opt] The element to draw (will draw all its children
--- as well). Defaults to `pop.screen`.
--- @see Element

pop.draw = (element=pop.screen) ->
    -- data.draw boolean controls an element and its children being drawn
    if element.data.draw
        if element.draw
            element\draw!
        for i = 1, #element.child
            pop.draw element.child[i]



--- Event handler for `love.mousemoved()`. (LÖVE >= 0.10.0)
--- @function mousemoved
--- @tparam integer x The x coordinate of the mouse.
--- @tparam integer y The y coordinate of the mouse.
--- @tparam number dx The distance on the x axis the mouse was moved.
--- @tparam number dy The distance on the y axis the mouse was moved.
--- @treturn boolean Was the event handled?

pop.mousemoved = (x, y, dx, dy) ->
    --- @todo Implement a way for an element to attach itself to `love.mousemoved()` events?
    if pop.focused and pop.focused.mousemoved
        return pop.focused\mousemoved x - pop.focused.data.x, y - pop.focused.data.y, dx, dy

    return false



--- Event handler for `love.mousepressed()`.
--- @function mousepressed
--- @tparam integer x The x coordinate of the mouse press.
--- @tparam integer y The y coordinate of the mouse press.
--- @tparam ?string|integer button The mouse button pressed. (Type varies by
--- LÖVE version.)
--- @tparam Element element[opt] The element to check for event handling (will
--- check its children as well). Defaults to `pop.screen`.
--- @treturn boolean Was the event handled?
--- @see Element

pop.mousepressed = (x, y, button, element) ->
    -- start at the screen, print that we received an event
    unless element
        log "mousepressed", x, y, button
        element = pop.screen

    -- have we handled the event?
    handled = false

    -- if it is inside the current element..
    if (x >= element.data.x) and (x <= element.data.x + element.data.w) and (y >= element.data.y) and (y <= element.data.y + element.data.h)
        -- check its child elements in reverse order, returning if something handles it
        for i = #element.child, 1, -1
            if handled = pop.mousepressed x, y, button, element.child[i]
                return handled

        -- if a child hasn't handled it yet (note: this check doesn't seem neccessary)
        unless handled
            -- if we can handle it and are visible, try to handle it, and set pop.focused
            if element.mousepressed and element.data.draw
                if handled = element\mousepressed x - element.data.x, y - element.data.y, button
                    pop.focused = element

    -- return whether or not we have handled the event
    return handled



--- Event handler for `love.mousereleased()`.
--- @function mousereleased
--- @tparam integer x The x coordinate of the mouse release.
--- @tparam integer y The y coordinate of the mouse release.
--- @tparam ?string|integer button The mouse button released. (Type varies by
--- LÖVE version.)
--- @tparam Element element[opt] The element to check for event handling (will
--- check its children as well). Defaults to `pop.screen`.
--- @treturn boolean Was a click handled?
--- @treturn boolean Was a mouse release handled?
--- @see Element

pop.mousereleased = (x, y, button, element) ->
    -- we are trying to handle a clicked or mousereleased event
    clickedHandled = false
    mousereleasedHandled = false

    -- if we have an element, and are within its bounds
    if element
        if (x >= element.data.x) and (x <= element.data.x + element.data.w) and (y >= element.data.y) and (y <= element.data.y + element.data.h)
            -- check its children in reverse for handling a clicked or mousereleased event
            for i = #element.child, 1, -1
                clickedHandled, mousereleasedHandled = pop.mousereleased x, y, button, element.child[i]
                if clickedHandled or mousereleasedHandled
                    return clickedHandled, mousereleasedHandled

            -- if that doesn't work, we try to handle it ourselves (note: again, this check seems unneccessary)
            unless clickedHandled or mousereleasedHandled
                -- clicked only happens on visible elements, mousereleased happens either way
                if element.clicked and element.data.draw
                    clickedHandled = element\clicked x - element.data.x, y - element.data.y, button
                if element.mousereleased
                    mousereleasedHandled = element\mousereleased x - element.data.x, y - element.data.y, button

                -- if we clicked, we're focused!
                if clickedHandled
                    pop.focused = element
                    --- @todo Figure out how to bring a focused element to the front of view (aka the first element in its parent's children).
                    --- (If I do it right here, the for loop above may break! I need to test/figure this out.)
                    --NOTE this might cause an error in the above for loop!
                    -- basically, move focused element to front of its parent's child
                    --element.parent\focusChild element
                    --table.insert element.parent, element.parent\removeChild(element),

    -- else, default to pop.screen to begin! (and print that we received an event)
    else
        log "mousereleased", x, y, button
        pop.mousereleased x, y, button, pop.screen

    return clickedHandled, mousereleasedHandled



--- Event handler for `love.keypressed()`.
--- @function keypressed
--- @tparam string key The key that was pressed.
--- @treturn boolean Was the event handled?

pop.keypressed = (key) ->
    log "keypressed", key

    -- keypressed events must be on visible elements
    element = pop.focused
    if element and element.keypressed and element.data.draw
        return element.keypressed key

    return false



--- Event handler for `love.keyreleased()`.
--- @function keyreleased
--- @tparam string key The key that was released.
--- @treturn boolean Was the event handled?

pop.keyreleased = (key) ->
    log "keyreleased", key

    -- keyreleased events are always called
    element = pop.focused
    if element and element.keyreleased
        return element.keyreleased key

    return false



--- Event handler for `love.textinput()`.
--- @function textinput
--- @tparam string text The text that was typed.
--- @treturn boolean Was the text input handled?

pop.textinput = (text) ->
    log "textinput", text

    -- textinput events must be on visible elements
    element = pop.focused
    if element and element.textinput and element.data.draw
        return element.textinput text

    return false



--- Draws simple rectangle outlines to debug placement of elements.
--- @function debugDraw
--- @tparam Element element[opt] The element to draw (will draw its children as
--- well). Defaults to `pop.screen`.
--- @see Element

pop.debugDraw = (element=pop.screen) ->
    --@todo Make this better in the future when different element types have been created and whatnot.
    if element.debugDraw
        element\debugDraw!
    else
        graphics.setLineWidth 1
        graphics.setColor 0, 0, 0, 100
        graphics.rectangle "fill", element.data.x, element.data.y, element.data.w, element.data.h
        graphics.setColor 150, 150, 150, 150
        graphics.rectangle "line", element.data.x, element.data.y, element.data.w, element.data.h
        graphics.setColor 200, 200, 200, 255
        graphics.print ".", element.data.x, element.data.y

    for i = 1, #element.child
        pop.debugDraw element.child[i]



--- Prints a basic structure of GUI elements with minimal info.
--- @function printElementTree
--- @tparam Element element[opt] The element to start at. Defaults to
--- `pop.screen`.
--- @see Element

pop.printElementTree = (element=pop.screen, depth=0) ->
    --- @todo Correct this once elements are reimplemented if it needs correction.
    cls = element.__class.__name

    if cls == "text"
        cls = cls .. " (\"#{element\getText!\gsub "\n", "\\n"}\")"
    elseif cls == "box"
        bg = element\getBackground!

        if type(bg) == "table"
            bg = "#{bg[1]}, #{bg[2]}, #{bg[3]}, #{bg[4]}"

        cls = cls .. " (#{bg})"

    log string.rep("-", depth) .. " #{cls}"

    for i = 1, #element.child
        pop.printElementTree element.child[i], depth + 1



-- finally, load is called and pop returned
pop.load!
return pop