#!/usr/bin/lua
-- -*- lua -*-

--
-- Copyright (c) 2008 Madcap BV (http://www.madcap.nl)
-- All rights reserved.
--
-- Permission is granted for use, copying, modification, distribution,
-- and distribution of modified versions of this work as long as the
-- above copyright notice is included.
--

-- needs a patch on ffmpeg/ffmpeg.c:
-- --- ffmpeg.c    (revision 11006)
-- +++ ffmpeg.c    (working copy)
-- @@ -999,7 +999,7 @@
--                    nb_frames_dup, nb_frames_drop);
--
--          if (verbose >= 0)
-- -            fprintf(stderr, "%s    \r", buf);
-- +            fprintf(stderr, "%s    \n", buf);
--
--          fflush(stderr);
--      }

local status_file
local status_tmp
local errors = {}

local error_markers = {
  "^(Error.*)$",
  "^(%[.*%]Error.*)$",
  "^(Unknown encoder.*)$",
  "(.*unrecognized option.*)",
  "(.*no such file or directory.*)",
  "(.*Unknown format.*)",
  "(.*Could not find codec parameters.*)",
  "(.*Assertion.*failed.*)",
  "(.*Segmentation fault.*)"
}

function write_status_file(status)
  local fd = io.open(status_tmp, "w")
  for k,v in pairs(status) do
    if k ~= "body" then
      fd:write(k .. ": " .. v .. "\n")
    end
  end
  if status.body then
    fd:write("\n" .. status.body .. "\n")
  end
  fd:close()
  os.execute("mv " .. status_tmp .. " " .. status_file)
end

function transcode(source_path, destination_path, hash, dst_ext, params)
  local duration = 0
  local command =
    string.format("ffmpeg -i %s/%s/%s %s -y %s/%s.%s 2>&1 &",
                  source_path, string.sub(hash, 1, 1), hash, params,
                  destination_path, hash, dst_ext)
  local fd = io.popen(command, "r")
  local line = fd:read("*l")
  local log = {}
  local output_seen = false

  while line do
    log[#log+1] = line

    if string.match(line, "^Output #0") then
      output_seen = true
    end

    local patt = string.match(line, "Duration: (.-),")
    if patt then
      local match_h, match_m, match_s = string.match(patt, "(%d+):(%d+):(.*)")
      local h, m, s = tonumber(match_h), tonumber(match_m), tonumber(match_s)
      if h and m and s then
        duration = h * 3600 + m * 60 + s
      else
        duration = 1
      end
    end

    local frame = string.match(line, "^frame=.-time=(.-) bitrate")
    if frame then
      write_status_file({ Status = "transcoding",
                          Progress = string.format("%.3f", frame / duration) })
    end

    for _,marker in pairs(error_markers) do
      local error = string.match(line, marker)
      if error then
        table.insert(errors, error)
      end
    end

    line = fd:read("*l")
  end
  fd:close()

  if next(errors) ~= nil then
    fd = io.open(status_file, "w")
    fd:write("Status: error\n")
    for _,e in pairs(errors) do
      fd:write("Errors: " .. e .. "\n")
    end
    fd:write("\nffmpeg-output: " .. table.concat(log, "}-{") .. "\n")
    fd:close()
  else
    write_status_file({ Status = "done",
                        Progress = "1.000",
                        Errors = "none",
                        Warnings = "none",
                        ffmpeg-output = table.concat(log, "}-{") })
  end
end

local source_path = arg[1]
local hash = arg[2]
local dst_ext = arg[3] or "avi"
local params = arg[4] or ""

if source_path == nil or hash == nil then
  print("Usage: vpx-transcode BASE_PATH HASH [extension] [\"ffmpeg parameters\"]")
  os.exit(1)
end

local destination_path = source_path .. "/transcode"

status_file = destination_path .. "/" .. hash .. ".status"
status_tmp = destination_path .. "/" .. hash .. ".status.tmp"

transcode(source_path, destination_path, hash, dst_ext, params)