-- @include constants.txt
-- @include track.txt
-- @include /koptilnya/libs/utils.txt
require("track.txt")
require("/koptilnya/libs/utils.txt")

local CONSTANTS = require("constants.txt")

function byteToHex(byte)
    return tostring(byte)
end

MidiPlayer = class("MidiPlayer")

function MidiPlayer:initialize()
    self._startTime = 0
    self._buffer = nil
    self._midiChunksByteLength = nil
    self._division = 0
    self._format = nil
    self._setIntervalId = false
    self._tracks = {}
    self._instruments = {}
    self._defaultTempo = 120
    self._tempo = null
    self._startTick = 0
    self._tick = 0
    self._lastTick = null
    self._inLoop = false
    self._totalTicks = 0
    self._events = {}
    self._totalEvents = 0
    self._eventListeners = {}
end

function MidiPlayer:loadURL(link)
    if not http.canRequest() then
        return
    end

    http.get(link, function(data, len)
        self._buffer = data

        self:_fileLoaded()
    end)
end

function MidiPlayer:_fileLoaded()
    if not self:isValid() then
        throw("Invalid MIDI file; should start with MThd")
    end

    self:setTempo(self._defaultTempo)
    self:_parseDivision()
    self:_parseFormat()
    self:_parseTracks()
end

function MidiPlayer:isValid()
    return string.char(unpack(byteTable(self._buffer, 1, 4))) == "MThd"
end

function MidiPlayer:setTempo(tempo)
    self._tempo = tempo
end

function MidiPlayer:_parseDivision()
    self._division = tonumber(bytesToHex(byteTable(self._buffer, 13, 2)))
end

function MidiPlayer:_parseFormat()
    self._format = tonumber(bytesToHex(byteTable(self._buffer, 9, 2)))
end

function MidiPlayer:_parseTracks()
    self._tracks = {}

    local offset = 1

    while offset < #self._buffer do
        local length = tonumber(bytesToHex(byteTable(self._buffer, offset + 4, 4)))

        if string.char(unpack(byteTable(self._buffer, offset, 4))) == "MTrk" then
            table.insert(self._tracks, MidiTrack:new(#self._tracks + 1, string.sub(self._buffer, offset + 8, offset + 8 + length)))
        end

        offset = offset + length + 8
    end
end

function MidiPlayer:resetTracks()
    for _, v in pairs(self._tracks) do
        v:reset()
    end
end

function MidiPlayer:enableTrack(id)
    self._tracks[id]:enable()
end

function MidiPlayer:disableTrack(id)
    self._tracks[id]:disable()
end