local async = require("diffview.async")
local lazy = require("diffview.lazy")

local DiffView = lazy.access("diffview.scene.views.diff.diff_view", "DiffView") ---@type DiffView|LazyModule
local FileEntry = lazy.access("diffview.scene.file_entry", "FileEntry") ---@type FileEntry|LazyModule
local FilePanel = lazy.access("diffview.scene.views.diff.file_panel", "FilePanel") ---@type FilePanel|LazyModule
local Rev = lazy.access("diffview.vcs.adapters.git.rev", "GitRev") ---@type GitRev|LazyModule
local RevType = lazy.access("diffview.vcs.rev", "RevType") ---@type RevType|LazyModule
local vcs_utils = lazy.require("diffview.vcs") ---@module "diffview.vcs"
local oop = lazy.require("diffview.oop") ---@module "diffview.oop"
local utils = lazy.require("diffview.utils") ---@module "diffview.utils"

local logger = DiffviewGlobal.logger

local M = {}

---@class FileData
---@field path string Path relative to git root.
---@field oldpath string|nil If the file has been renamed, this should be the old path, oterhwise nil.
---@field status string Git status symbol.
---@field stats GitStats|nil
---@field left_null boolean Indicates that the left buffer should be represented by the null buffer.
---@field right_null boolean Indicates that the right buffer should be represented by the null buffer.
---@field selected boolean|nil Indicates that this should be the initially selected file.

---@class CDiffView : DiffView
---@field files any
---@field fetch_files function A function that should return an updated list of files.
---@field get_file_data function A function that is called with parameters `path: string` and `split: string`, and should return a list of lines that should make up the buffer.
local CDiffView = oop.create_class("CDiffView", DiffView.__get())

---CDiffView constructor.
---@param opt any
function CDiffView:init(opt)
  logger:info("[api] Creating a new Custom DiffView.")
  self.valid = false

  local err, adapter = vcs_utils.get_adapter({ top_indicators = { opt.git_root } })

  if err then
    utils.err(
      ("Failed to create an adapter for the repository: %s")
      :format(utils.str_quote(opt.git_root))
    )
    return
  end

  ---@cast adapter -?

  -- Fix malformed revs
  for _, v in ipairs({ "left", "right" }) do
    local rev = opt[v]
    if not rev or not rev.type then
      opt[v] = Rev(RevType.STAGE, 0)
    end
  end

  self.fetch_files = opt.update_files
  self.get_file_data = opt.get_file_data

  self:super(vim.tbl_extend("force", opt, {
    adapter = adapter,
    panel = FilePanel(
      adapter,
      self.files,
      self.path_args,
      self.rev_arg or adapter:rev_to_pretty_string(opt.left, opt.right)
    ),
  }))

  if type(opt.files) == "table" and not vim.tbl_isempty(opt.files) then
    local files = self:create_file_entries(opt.files)

    for kind, entries in pairs(files) do
      for _, entry in ipairs(entries) do
        table.insert(self.files[kind], entry)
      end
    end
    self.files:update_file_trees()

    if self.panel.cur_file then
      vim.schedule(function()
        self:set_file(self.panel.cur_file, false, true)
      end)
    end
  end

  self.valid = true
end

---@override
CDiffView.get_updated_files = async.wrap(function(self, callback)
  local err

  repeat
    local ok, new_files = pcall(self.fetch_files, self)

    if not ok or type(new_files) ~= "table" then
      err = { "Integrating plugin failed to provide file data!" }
      break
    end

    ---@diagnostic disable-next-line: redefined-local
    local ok, entries = pcall(self.create_file_entries, self, new_files)

    if not ok then
      err = { "Integrating plugin provided malformed file data!" }
      break
    end

    callback(nil, entries)
    return
  until true

  utils.err(err, true)
  logger:error(table.concat(err, "\n"))
  callback(err, nil)
end)

function CDiffView:create_file_entries(files)
  local entries = {}

  local sections = {
    { kind = "conflicting", files = files.conflicting or {} },
    { kind = "working", files = files.working or {}, left = self.left, right = self.right },
    {
      kind = "staged",
      files = files.staged or {},
      left = self.adapter:head_rev(),
      right = Rev(RevType.STAGE, 0),
    },
  }

  for _, v in ipairs(sections) do
    entries[v.kind] = {}

    for _, file_data in ipairs(v.files) do
      if v.kind == "conflicting" then
        table.insert(entries[v.kind], FileEntry.with_layout(CDiffView.get_default_merge_layout(), {
          adapter = self.adapter,
          path = file_data.path,
          oldpath = file_data.oldpath,
          status = "U",
          kind = "conflicting",
          revs = {
            a = Rev(RevType.STAGE, 2),
            b = Rev(RevType.LOCAL),
            c = Rev(RevType.STAGE, 3),
            d = Rev(RevType.STAGE, 1),
          },
        }))
      else
        table.insert(entries[v.kind], FileEntry.with_layout(CDiffView.get_default_layout(), {
          adapter = self.adapter,
          path = file_data.path,
          oldpath = file_data.oldpath,
          status = file_data.status,
          stats = file_data.stats,
          kind = v.kind,
          revs = {
            a = v.left,
            b = v.right,
          },
          get_data = self.get_file_data,
          --FIXME: left_null, right_null
        }))
      end

      if file_data.selected then
        self.panel:set_cur_file(entries[v.kind][#entries[v.kind]])
      end
    end
  end

  return entries
end

M.CDiffView = CDiffView
return M