(** Tailwind CLI integration for CSS processing *)

open Unix

type config = {
  input_css: string;  (** Path to input CSS file with Tailwind directives *)
  output_css: string; (** Path to output CSS file *)
  content: string list; (** List of content paths to scan for classes *)
  minify: bool; (** Whether to minify the output *)
}

let default_config = {
  input_css = "input.css";
  output_css = "output.css";
  content = ["*.html"; "*.ml"];
  minify = true;
}

(** Check if Tailwind CLI is available *)
let check_tailwind_cli () =
  try
    let ic = open_process_in "npx @tailwindcss/cli --help 2>/dev/null" in
    let _ = input_line ic in
    let status = close_process_in ic in
    status = WEXITED 0
  with _ -> false

(** Generate Tailwind CSS from input file *)
let process_css config =
  if not (check_tailwind_cli ()) then
    failwith "Tailwind CLI not found. Install with: npm install -D @tailwindcss/cli"
  else
    let content_args = String.concat " " (List.map (fun p -> Printf.sprintf "--content '%s'" p) config.content) in
    let minify_flag = if config.minify then "--minify" else "" in
    let cmd = Printf.sprintf "npx @tailwindcss/cli -i %s -o %s %s %s 2>&1"
      config.input_css
      config.output_css
      content_args
      minify_flag
    in
    let ic = open_process_in cmd in
    let rec read_output acc =
      try
        let line = input_line ic in
        read_output (line :: acc)
      with End_of_file ->
        List.rev acc
    in
    let output = read_output [] in
    let status = close_process_in ic in
    match status with
    | WEXITED 0 -> Ok output
    | WEXITED n -> Error (Printf.sprintf "Tailwind CLI exited with code %d:\n%s" n (String.concat "\n" output))
    | _ -> Error "Tailwind CLI terminated abnormally"

(** Process CSS for a specific HTML file *)
let process_for_html ~input_css ~html_file ~output_css ?(minify=true) () =
  let config = {
    input_css;
    output_css;
    content = [html_file];
    minify;
  } in
  process_css config

(** Write HTML to file and process CSS *)
let write_and_process ~html_content ~html_file ~input_css ~output_css () =
  (* Write HTML to file *)
  let oc = open_out html_file in
  output_string oc html_content;
  close_out oc;
  
  (* Process CSS *)
  match process_for_html ~input_css ~html_file ~output_css () with
  | Ok _ -> 
    Printf.eprintf "✅ Generated %s and %s\n" html_file output_css;
    Ok ()
  | Error msg ->
    Printf.eprintf "❌ CSS processing failed: %s\n" msg;
    Error msg