import { APP_NAME } from "./constants.ts";
import { notificationToSafeLine, type TerminalNotification } from "./notify-protocol.ts";

export const OSC99_UNSAFE = /[\u0000-\u001f\u007f-\u009f]/u;
export const OSC99_MAX_PAYLOAD_BYTES = 2048;
export const OSC99_APP_NAME = APP_NAME;
let nextNotificationId = 1;

function base64Utf8(value: string): string {
  return Buffer.from(value, "utf8").toString("base64");
}

export function sanitizeOsc99Id(id: string | undefined): string {
  if (!id) return "";
  const safe = id.replace(/[^a-zA-Z0-9_+\-.]/gu, "");
  return safe === "0" ? "" : safe;
}

function osc99Id(id: string | undefined): string {
  return sanitizeOsc99Id(id) || `pi-${nextNotificationId++}`;
}

export function utf8CodePointBytes(character: string): number {
  const codePoint = character.codePointAt(0) ?? 0;
  return codePoint <= 0x7f ? 1 : codePoint <= 0x7ff ? 2 : codePoint <= 0xffff ? 3 : 4;
}

export function chunkUtf8(payload: string): string[] {
  if (payload === "") return [""];
  const chunks: string[] = [];
  let start = 0;
  let index = 0;
  let bytes = 0;
  for (const character of payload) {
    const characterBytes = utf8CodePointBytes(character);
    if (bytes > 0 && bytes + characterBytes > OSC99_MAX_PAYLOAD_BYTES) {
      chunks.push(payload.slice(start, index));
      start = index;
      bytes = 0;
    }
    bytes += characterBytes;
    index += character.length;
  }
  chunks.push(payload.slice(start));
  return chunks;
}

function osc99Chunk(meta: string[], payload: string): string {
  if (OSC99_UNSAFE.test(payload)) {
    return `\x1b]99;${[...meta, "e=1"].join(":")};${base64Utf8(payload)}\x1b\\`;
  }
  return `\x1b]99;${meta.join(":")};${payload}\x1b\\`;
}

function osc99Payload(meta: string[], payload: string, holdUntilLaterPayload: boolean): string {
  const chunks = chunkUtf8(payload);
  return chunks.map((chunk, index) => {
    const chunkMeta = [...meta];
    if (holdUntilLaterPayload || index < chunks.length - 1) chunkMeta.push("d=0");
    return osc99Chunk(chunkMeta, chunk);
  }).join("");
}

export function osc99Urgency(urgency: TerminalNotification["urgency"]): string | undefined {
  return urgency === "low" ? "0" : urgency === "normal" ? "1" : urgency === "critical" ? "2" : undefined;
}

export function osc99Actions(actions: TerminalNotification["actions"]): string | undefined {
  switch (actions) {
    case "focus": return "focus";
    case "report": return "report";
    case "focus-report": return "focus,report";
    case "none": return "-focus";
    default: return undefined;
  }
}

export function formatOsc99Notification(notification: TerminalNotification): string {
  const id = osc99Id(notification.id);
  const meta = [`i=${id}`, `f=${base64Utf8(OSC99_APP_NAME)}`];
  const action = osc99Actions(notification.actions);
  const urgency = osc99Urgency(notification.urgency);
  if (action) meta.push(`a=${action}`);
  if (urgency) meta.push(`u=${urgency}`);
  const types = notification.type === undefined ? [] : Array.isArray(notification.type) ? notification.type : [notification.type];
  for (const type of types) meta.push(`t=${base64Utf8(type)}`);
  if (notification.iconName) meta.push(`n=${base64Utf8(notification.iconName)}`);
  if (notification.sound) meta.push(`s=${base64Utf8(notification.sound)}`);
  if (notification.expiresMs !== undefined && Number.isFinite(notification.expiresMs)) meta.push(`w=${Math.max(-1, Math.trunc(notification.expiresMs))}`);
  const title = notification.title ?? notification.body ?? "";
  const body = notification.title ? notification.body : undefined;
  if (body !== undefined && body !== "") return osc99Payload(meta, title, true) + osc99Payload([`i=${id}`, "p=body"], body, false);
  return osc99Payload(meta, title, false);
}

export function formatOsc9(input: TerminalNotification): string {
  return `\x1b]9;${notificationToSafeLine(input)}\x1b\\`;
}

export function formatCollapsedOsc99(input: TerminalNotification): string {
  return `\x1b]99;;${notificationToSafeLine(input)}\x1b\\`;
}

/** Rich OSC 99 is opt-in; no stdin probe or mutable capability state exists. */
export function formatNotification(input: string | TerminalNotification, protocol: string, rich = false): string {
  if (protocol === "\x07") return "\x07";
  if (typeof input === "string") {
    const safe = input.replace(/[\u0000-\u001f\u007f-\u009f]/gu, " ");
    return `${protocol}${safe}\x1b\\`;
  }
  if (protocol === "\x1b]99;;" && rich) return formatOsc99Notification(input);
  return protocol === "\x1b]9;" ? formatOsc9(input) : formatCollapsedOsc99(input);
}