--[[
Eat It - a Mpv plugin manager

Copyright © 2023 squibid

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
]]

-- NOTE: This is a POC and will most likely be reimplimented using diff files
-- with git
-- or we might want to generate a diff file from the requested changes
-- and check if the diffs match in content

--[[ 
                           Lua Script Script Injector
Takes an input file and code then, it outputs a file with your code in there.
]]--

local mp = require('mp')

mod = {
  version = 'ALPHA 1', -- the current version of lssi
  author = 'squibid',
}

-- load the eatit config file
dofile(mp.command_native({'expand-path', '~~/eatit-cfg.lua'}))

-- helper functions
local function tablelength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

local function fileexists(name)
   local f = io.open(name, 'r')
   if f ~= nil then io.close(f) return true else return false end
end

local function logwrite(string)
  if opts.logging.log then
    io.write(os.date(opts.logging.logdate) .. ' ' .. string .. '\n')
  end
end

local function openlog()
  if opts.logging.log then -- log if asked to
    -- get our logfile's full path
    fn = mp.command_native({'expand-path', opts.logging.logfile})

    f = io.open(fn, 'a') -- open file buffer
    io.output(f) -- set it as default
  end
end

local function closelog()
  if opts.logging.log then
    io.close(f)
  end
end

local function inject(infile, l, outfile)
  local inf = io.open(infile, 'r')
  local infcont = {}
  for i in inf:lines() do
    table.insert(infcont, i)
  end
  inf:close()

  -- don't do anything if there is already code injected into the file
  if string.find(infcont[1], "-- code injected by lssi") then
    logwrite('code is already injected into ' .. infile)
    return
  end
  logwrite('Injecting code into ' .. infile)

  for i in pairs(l) do
    -- add requested line below existing line
    if l[i][2] == 'G' then
      infcont[tablelength(infcont)] = infcont[tablelength(infcont)] .. '\n' .. l[i][1]
    elseif l[i][2] == 'g' then
      infcont[1] = l[i][1] .. '\n' .. infcont[1]
    else
      infcont[l[i][2]] = (infcont[l[i][2]]) .. '\n' .. l[i][1]
    end
  end

  local outf = io.open(outfile, 'w')

  -- we inject metadata to prevent writing to the file more than once
  infcont[1] = "-- code injected by lssi " .. mod.version .. '\n' .. infcont[1]
  for i, v in ipairs(infcont) do
    outf:write(v .. '\n')
  end

  io.close(outf)
end

local function checkandinject()
  openlog()

  for i = 1, tablelength(plugins) do
    -- get the file we want to inject our code into
    local f = mp.command_native({'expand-path', '~~/'}) ..
      '/' .. plugins[i]['dir'] ..
      '/' .. plugins[i]['file']

    -- check if the plugin has been configured with lssi
    if plugins[i]['lssi'] then
      -- and the file we are trying to modify actually exists
      if fileexists(f) then
        -- inject it! no going back now
        inject(f, plugins[i]['lssi'], f)
      else
        logwrite('Failed to inject code into "' ..
          plugins[i]['file'] .. '" file does not exist')
      end
    end
  end

  closelog()
end

checkandinject()