local M = {}

local config = require("denote-fzf-lua.config")
local fzflua = require("fzf-lua")
local builtin = require("fzf-lua.previewer.builtin")

local FIELDS = { "path", "date", "time", "sig", "title", "keywords", "ext" }

local function list_denote_files(dir)
  local results = {}
  local stack = { vim.fn.expand(dir) }

  while #stack > 0 do
    local current = table.remove(stack)
    local ok, entries = pcall(vim.fn.readdir, current)
    if ok then
      for _, entry in ipairs(entries) do
        local full = current .. "/" .. entry
        local stat = vim.loop.fs_stat(full)
        if stat then
          if stat.type == "directory" then
            table.insert(stack, full)
          elseif stat.type == "file" and entry:match("^%d%d%d%d%d%d%d%dT%d%d%d%d%d%d") then
            table.insert(results, full)
          end
        end
      end
    end
  end

  return results
end

local function parse_denote(basename)
  local dt = basename:sub(1, 15)
  if not dt:match("^%d%d%d%d%d%d%d%dT%d%d%d%d%d%d$") then return nil end

  local date = dt:sub(1, 4) .. "-" .. dt:sub(5, 6) .. "-" .. dt:sub(7, 8)
  local time = dt:sub(10, 11) .. ":" .. dt:sub(12, 13) .. ":" .. dt:sub(14, 15)

  local dot_idx = basename:find("%.", 16, true)
  if not dot_idx then return nil end
  local ext = basename:sub(dot_idx)
  local body = basename:sub(16, dot_idx - 1)

  local sig, title, keywords = "", "", ""
  local pos = 1

  if body:sub(pos, pos + 1) == "==" then
    local sig_end = body:find("%-%-", pos + 2)
    if sig_end then
      sig = body:sub(pos + 2, sig_end - 1)
      pos = sig_end
    end
  end

  if body:sub(pos, pos + 1) == "--" then
    local title_end = body:find("__", pos + 2)
    if title_end then
      title = body:sub(pos + 2, title_end - 1)
      pos = title_end
    else
      title = body:sub(pos + 2)
      pos = #body + 1
    end
  else
    return nil
  end

  if pos <= #body and body:sub(pos) == "__" then
    keywords = body:sub(pos + 2)
  end

  return {
    path     = "",
    date     = date,
    time     = time,
    sig      = sig ~= "" and sig:gsub("=", " ") or ".",
    title    = title ~= "" and title:gsub("%-", " ") or ".",
    keywords = keywords ~= "" and keywords:gsub("_", " ") or ".",
    ext      = ext,
  }
end

local function format_denote_table(files)
  local parsed = {}
  for _, filepath in ipairs(files) do
    local basename = vim.fn.fnamemodify(filepath, ":t")
    local dirpath = vim.fn.fnamemodify(filepath, ":h") .. "/"
    local info = parse_denote(basename)
    if info then
      info.path = dirpath
      table.insert(parsed, info)
    end
  end

  local widths = {}
  for i, field in ipairs(FIELDS) do
    widths[i] = #field
  end
  for _, info in ipairs(parsed) do
    for i, field in ipairs(FIELDS) do
      widths[i] = math.max(widths[i], #info[field])
    end
  end

  local lines = {}
  local parts = {}
  for i, field in ipairs(FIELDS) do
    parts[i] = string.format("%-" .. widths[i] .. "s", field)
  end
  table.insert(lines, table.concat(parts, "  "))

  for _, info in ipairs(parsed) do
    parts = {}
    for i, field in ipairs(FIELDS) do
      parts[i] = string.format("%-" .. widths[i] .. "s", info[field])
    end
    table.insert(lines, table.concat(parts, "  "))
  end

  return lines
end

M.reconstruct_previewer = builtin.buffer_or_file:extend()

function M.reconstruct_previewer:new(o, opts, fzf_win)
  M.reconstruct_previewer.super.new(self, o, opts, fzf_win)
  setmetatable(self, M.reconstruct_previewer)
  return self
end

function M.reconstruct_previewer:parse_entry(entry_str)
  return {
    path = M.reconstruct_filename(entry_str),
    line = 1,
    col = 1,
  }
end

local function format_field(field, delim)
  if field == "." then return "" end
  return delim .. delim .. field:gsub("%s", delim)
end

function M.reconstruct_filename(row)
  if not row or row == "" then return "" end
  local t = {}
  row = row:gsub("%s%s+", "|")
  t.path, t.year, t.month, t.day, t.hour, t.min, t.sec, t.sig, t.title, t.keywords, t.ext =
    row:match("^(.*/)|(%d%d%d%d)%-(%d%d)%-(%d%d)|(%d%d):(%d%d):(%d%d)|([^|]+)|([^|]+)|([^|]+)|(%..+)")
  if not t.path then return "" end
  t.sig      = format_field(t.sig, "=")
  t.title    = format_field(t.title, "-")
  t.keywords = format_field(t.keywords, "_")
  return t.path .. t.year .. t.month .. t.day .. "T" .. t.hour .. t.min .. t.sec .. t.sig .. t.title .. t.keywords .. t.ext
end

function M.format_fzf_with_nth(options)
  local indices = {}
  for i, field in ipairs(FIELDS) do
    if options.search_fields[field] then
      table.insert(indices, i)
    end
  end
  return table.concat(indices, ",")
end

function M.search_files(options)
  local files = list_denote_files(options.dir)
  local lines = format_denote_table(files)

  local opts = {}
  opts.previewer = M.reconstruct_previewer
  opts.fzf_opts = vim.deepcopy(options.fzf_lua_opts.fzf_opts)
  opts.fzf_opts["--with-nth"] = M.format_fzf_with_nth(options)
  opts.fzf_opts["--header-lines"] = 1
  opts.fzf_opts["--delimiter"] = "\\s{2,}"
  opts.actions = {
    default = function(selected)
      local filename = M.reconstruct_filename(selected[1])
      vim.api.nvim_command("edit " .. vim.fn.fnameescape(filename))
    end,
  }
  fzflua.fzf_exec(lines, opts)
end

function M.search_contents(options)
  if vim.fn.executable("rg") ~= 1 then
    vim.notify("denote-fzf-lua: ripgrep is required for content search", vim.log.levels.WARN)
    return
  end
  local opts = {}
  opts.cwd = options.dir
  opts.previewer = "builtin"
  opts.fzf_opts = options.fzf_lua_opts.fzf_opts
  opts.actions = fzflua.defaults.actions.files
  fzflua.fzf_live(function(query)
    local q = type(query) == "table" and table.concat(query, " ") or query or ""
    return "rg --column --color=always -i -- " .. vim.fn.shellescape(q)
  end, opts)
end

function M.load_cmd(options)
  vim.api.nvim_create_user_command("DenoteSearch", function(opts)
    if opts.fargs[1] == "files" then
      M.search_files(options)
    elseif opts.fargs[1] == "contents" then
      M.search_contents(options)
    else
      error("Unsupported operation " .. opts.fargs[1])
    end
  end, {
    nargs = 1,
    complete = function()
      return { "files", "contents" }
    end,
  })
end

function M.setup(options)
  options = vim.tbl_deep_extend("force", config.defaults, options or {})
  fzflua.setup(options.fzf_lua_opts)
  M.load_cmd(options)
end

return M