-- Copyright (c) 2024 squibid, see LICENSE file for more info
local mp = require('mp')
local msg = require('mp.msg')
local utils = require('mp.utils')

local proc = require('proc')

-- load the config file
local config = dofile(mp.command_native({"expand-path", "~~/eatit-cfg.lua"}))
if not config or type(config) ~= "table" then
  msg.fatal("no config provided, bailing out")
  return
end

local base_dir = mp.command_native({"expand-path", "~~cache/plugins"})
local packages = {}

-- make sure the base directory exists (*nix only)
if utils.file_info(base_dir) == nil then
  proc.exec({ "mkdir", "-p", base_dir }, {}, function(err, message)
    if err then
      msg.fatal(string.format("failed to create plugin directory: %s", err))
      return
    end
  end)
end

--- regiester a new package spec
---@param spec table package spec from config
---@return table package
local function register_pkg(spec)
  if type(spec) ~= "table" then
    spec = { spec }
  end

  local id = spec[1]
  local package = packages[id]

  if not package then
    package = {
      id = id,
      exists = false,
      setup = false
    }

    packages[id] = package
  end

  package.name = string.sub(package.id, string.find(package.id, "%/") + 1, #package.id)
  package.url = spec.url or ("https://github.com/"..package.id..".git")
  package.branch = spec.branch
  package.files = spec.files
  package.dir = package.files and utils.join_path(base_dir, package.name) or utils.join_path(mp.command_native({ 'expand-path', "~~/scripts" }), package.name)
  package.pin = spec.pin

  package.exists = utils.file_info(package.dir) ~= nil
  -- validate that all files have been installed
  if type(package.files) == "table" then
    for filename, dest in pairs(package.files) do
      if not utils.file_info(utils.join_path(package.dir, filename)) or
        not utils.file_info(utils.join_path(mp.command_native({ "expand-path", dest }), filename)) then
        package.exists = false
        break
      end
    end
  end

  package.on_setup = spec.setup

  return package
end

--- run package setup
---@param package table package
local function setup_package(package)
  if type(package.on_setup) ~= "function" then
    return
  end

  local ok, err = pcall(package.on_setup, package.dir)
  if not ok then
    msg.warn(string.format("error when running setup on '%s': %s", package.id, err))
    return
  end
  package.setup = true
end

--- copy all files according to package spec
---@param package table package
local function copy_files(package)
  --- copy src to dest
  ---@param src string path to src file
  ---@param dest string path to dest file
  local function cp(src, dest)
    local i = io.open(src, 'r')
    if not i then return end
    local o = io.open(dest, 'w')
    if not o then return end
    o:write(i:read('*a'))
    o:close()
    i:close()
  end

  if type(package.files) == "table" then
    for name, loc in pairs(package.files) do
      local path = mp.command_native({'expand-path', loc})
      local dest = utils.join_path(path, name)

      local src = utils.join_path(package.dir, name)
      if not utils.file_info(src) then
        msg.warn(string.format("file %s not found", name))
        return
      end
      local ok, err = pcall(cp, src, dest)
      if not ok then
        msg.warn(string.format("failed to copy %s: %s", name, utils.to_string(err)))
      end
    end
  end
end

local function validate_package()
end

--- download or update package
---@param package table package
---@param cb function callback
local function sync(package, cb)
  if package.exists then
    if package.pin then
      cb()
      return
    end

    --- generic error
    ---@param err any error
    local function log_err(err)
      msg.error(string.format("failed to update %s; reason: %s", package.id, err))
    end

    -- get current head commit hash
    proc.git_rev_parse(package.dir, "HEAD", function(err, before)
      if err then
        log_err(before)
        cb(err)
        return
      end

      -- get the latest commit hash
      proc.git_fetch(package.dir, "origin", package.branch or "HEAD", function(err, message)
        if err then
          log_err(message)
          cb(err)
          return
        end

        -- check the latest and current against eachother
        proc.git_rev_parse(package.dir, "FETCH_HEAD", function(err, after)
          if err then
            log_err(after)
            cb(err)
            return
          elseif before == after then
            msg.info(string.format("skipped %s", package.id))
            cb(err)
            return
          end

          -- switch HEAD to new commit
          proc.git_reset(package.dir, after, function(err, message)
            if err then
              log_err(message)
              return
            end
            setup_package(package)
            copy_files(package)
            msg.info(string.format("updated %s; %s -> %s", package.id, before, after))

            cb(err)
          end)
        end)
      end)
    end)
  else
    -- clone repo since it doesn't exist
    proc.git_clone(package.dir, package.url, package.branch, function(err, message)
      if err then
        msg.error(string.format("failed to install %s; reason: %s", package.id, utils.to_string(message)))
      else
        setup_package(package)
        copy_files(package)
        package.exists = true
        msg.info(string.format("installed %s", package.id))
      end

      cb(err)
    end)
  end
end

--- sync a list of plugins
---@param list table list of packages
---@param cb function callback
local function sync_list(list, cb)
  local progress = 0

  for i in pairs(list) do
    sync(list[i], function()
      progress = progress + 1
      cb()
    end)
  end
end

--- check if package spec should be synced
---@param package table package
---@return boolean
local function should_sync(package)
  if config.sync == "new" or config.sync == nil then
    return not package.exists
  else
    return config.sync == "always"
  end
end

-- register all packages
for i = 1, #config do
  local ok, err = pcall(register_pkg, config[i])
  if not ok then
    msg.warn(string.format("%s: %s", err, config[i].as))
  end
end

-- check for package updates
local targets = {}
for i in pairs(packages) do
  if should_sync(packages[i]) then
    targets[#targets + 1] = packages[i]
  end
end

sync_list(targets, function() end)

-- register script message for keybinding
mp.register_script_message("eatit-sync", function(name, value)
  sync_list(packages, function() end)
end)