-- lua/chatgpt_nvim/context.lua
-- Modified to:
-- 1) Use directories from config to build project structure.
-- 2) Include file contents from those directories.
-- 3) Skip files listed in .gitignore.
--

local M = {}

local uv = vim.loop

-- Returns a set of files mentioned in .gitignore patterns.
local function load_gitignore_patterns(root)
  local gitignore_path = root .. "/.gitignore"
  local fd = uv.fs_open(gitignore_path, "r", 438)
  if not fd then
    return {}
  end
  local stat = uv.fs_fstat(fd)
  local data = uv.fs_read(fd, stat.size, 0)
  uv.fs_close(fd)
  if not data then return {} end
  local patterns = {}
  for line in data:gmatch("[^\r\n]+") do
    line = line:match("^%s*(.-)%s*$") -- trim
    if line ~= "" and not line:match("^#") then
      patterns[#patterns+1] = line
    end
  end
  return patterns
end

local function should_ignore_file(file, ignore_patterns)
  for _, pattern in ipairs(ignore_patterns) do
    -- Simple pattern matching. For more complex patterns, consider using lua patterns.
    -- This is a basic implementation. Adjust as needed.
    if file:find(pattern, 1, true) then
      return true
    end
  end
  return false
end

local function scandir(dir, ignore_patterns, files)
  files = files or {}
  local fd = uv.fs_opendir(dir, nil, 50)
  if not fd then return files end
  while true do
    local ents = uv.fs_readdir(fd)
    if not ents then break end
    for _, ent in ipairs(ents) do
      local fullpath = dir .. "/" .. ent.name
      if not should_ignore_file(fullpath, ignore_patterns) then
        if ent.type == "file" then
          table.insert(files, fullpath)
        elseif ent.type == "directory" and ent.name ~= ".git" then
          scandir(fullpath, ignore_patterns, files)
        end
      end
    end
  end
  uv.fs_closedir(fd)
  return files
end

function M.get_project_files(directories)
  local root = vim.fn.getcwd()
  local ignore_patterns = load_gitignore_patterns(root)
  local all_files = {}
  for _, dir in ipairs(directories) do
    local abs_dir = dir
    if not abs_dir:match("^/") then
      abs_dir = root .. "/" .. dir
    end
    scandir(abs_dir, ignore_patterns, all_files)
  end
  return all_files
end

function M.get_project_structure(directories)
  local files = M.get_project_files(directories)
  -- Create a listing of files only (relative to root)
  local root = vim.fn.getcwd()
  local rel_files = {}
  for _, f in ipairs(files) do
    local rel = f:gsub("^" .. root .. "/", "")
    table.insert(rel_files, rel)
  end

  local structure = "Files:\n" .. table.concat(rel_files, "\n")
  return structure
end

function M.get_file_contents(files)
  local root = vim.fn.getcwd()
  local sections = {}
  for _, f in ipairs(files) do
    local fd = uv.fs_open(root .. "/" .. f, "r", 438)
    if fd then
      local stat = uv.fs_fstat(fd)
      local data = uv.fs_read(fd, stat.size, 0)
      uv.fs_close(fd)
      if data then
        table.insert(sections, "\n<<<CGPT Current File\n" .. (root .. "/" .. f) .. "\n" .. data .. "\n<<<CGPT Current File END\n")
      end
    end
  end
  return table.concat(sections, "\n")
end

function M.get_current_file()
  local current_path = vim.fn.expand("%:p")
  if current_path == "" then
    return nil, nil
  end
  local fd = uv.fs_open(current_path, "r", 438)
  if not fd then return nil, current_path end
  local stat = uv.fs_fstat(fd)
  local data = uv.fs_read(fd, stat.size, 0)
  uv.fs_close(fd)
  return data, current_path
end

function M.get_readme_content()
  local root = vim.fn.getcwd()
  local fd = uv.fs_open(root .. "/README.md", "r", 438)
  if not fd then return nil end
  local stat = uv.fs_fstat(fd)
  local data = uv.fs_read(fd, stat.size, 0)
  uv.fs_close(fd)
  return data
end

return M