import { findTask, onEach, state } from "./state.js";

type Saved = {
  composer: Record<string, { text: string; images: number }>;
  checked: Record<string, string[]>;
  texts: Record<string, string>;
};

const composerTexts = new Map<string, string>();
const composerImages = new Map<string, number>();
type Send = { key: string; text: string; images: number };

const sending = new Set<Send>();
const lostImages = new Map<string, number>();
const checked = new Map<string, string[]>();
const texts = new Map<string, string>();

let storeKey: string | undefined;
let timer = 0;

export function loadDrafts(): void {
  storeKey = `byre.drafts.${state.me!.login}`;
  const saved = readSaved(storeKey);
  for (const [key, d] of Object.entries(saved.composer)) {
    if (d.text) {
      composerTexts.set(key, d.text);
    }
    if (d.images > 0) {
      lostImages.set(key, d.images);
    }
  }
  for (const [id, opts] of Object.entries(saved.checked)) {
    checked.set(id, opts);
  }
  for (const [id, text] of Object.entries(saved.texts)) {
    texts.set(id, text);
  }
  prune();
  onEach(["tasks", "inbox"], prune);
  addEventListener("pagehide", flushDrafts);
}

function readSaved(key: string): Saved {
  const out: Saved = { composer: {}, checked: {}, texts: {} };
  let raw: unknown;
  try {
    raw = JSON.parse(localStorage.getItem(key) ?? "{}");
  } catch (err) {
    console.error("read drafts", err);
    return out;
  }
  if (!isRecord(raw)) {
    return out;
  }
  for (const [k, v] of Object.entries(isRecord(raw["composer"]) ? raw["composer"] : {})) {
    if (isRecord(v) && typeof v["text"] === "string" && typeof v["images"] === "number") {
      out.composer[k] = { text: v["text"], images: v["images"] };
    }
  }
  for (const [k, v] of Object.entries(isRecord(raw["checked"]) ? raw["checked"] : {})) {
    if (Array.isArray(v) && v.every((o) => typeof o === "string")) {
      out.checked[k] = v as string[];
    }
  }
  for (const [k, v] of Object.entries(isRecord(raw["texts"]) ? raw["texts"] : {})) {
    if (typeof v === "string") {
      out.texts[k] = v;
    }
  }
  return out;
}

function isRecord(v: unknown): v is Record<string, unknown> {
  return typeof v === "object" && v !== null && !Array.isArray(v);
}

function prune(): void {
  let changed = false;
  for (const map of [composerTexts, composerImages, lostImages]) {
    for (const key of map.keys()) {
      const taskId = key.replace(/^message:/, "");
      if (taskId !== "lead" && findTask(taskId)?.status !== "active") {
        map.delete(key);
        changed = true;
      }
    }
  }
  for (const map of [checked, texts]) {
    for (const id of map.keys()) {
      if (!state.inbox.some((i) => i.id === id)) {
        map.delete(id);
        changed = true;
      }
    }
  }
  if (changed) {
    save();
  }
}

function save(): void {
  clearTimeout(timer);
  timer = setTimeout(flushDrafts, 400);
}

export function flushDrafts(): void {
  clearTimeout(timer);
  timer = 0;
  if (!storeKey) {
    return;
  }
  const out: Saved = { composer: {}, checked: Object.fromEntries(checked), texts: Object.fromEntries(texts) };
  const keys = new Set([...composerTexts.keys(), ...composerImages.keys(), ...[...sending].map((s) => s.key), ...lostImages.keys()]);
  for (const key of keys) {
    const inFlight = [...sending].filter((s) => s.key === key);
    const text = [...inFlight.map((s) => s.text), composerTexts.get(key) ?? ""].filter((t) => t).join("\n\n");
    const images = (composerImages.get(key) ?? 0) + inFlight.reduce((n, s) => n + s.images, 0) + (lostImages.get(key) ?? 0);
    if (text || images > 0) {
      out.composer[key] = { text, images };
    }
  }
  try {
    localStorage.setItem(storeKey, JSON.stringify(out));
  } catch (err) {
    console.error("save drafts", err);
  }
}

export function composerText(key: string): string {
  return composerTexts.get(key) ?? "";
}

export function setComposerText(key: string, text: string): void {
  if (text) {
    composerTexts.set(key, text);
  } else {
    composerTexts.delete(key);
  }
  save();
}

export function setComposerImages(key: string, n: number): void {
  if (n > 0) {
    composerImages.set(key, n);
  } else {
    composerImages.delete(key);
  }
  save();
}

export function lostImageCount(key: string): number {
  return lostImages.get(key) ?? 0;
}

export function forgetLostImages(key: string): void {
  lostImages.delete(key);
  save();
}

export function startSend(key: string, text: string, images: number): Send {
  const send = { key, text, images };
  sending.add(send);
  composerTexts.delete(key);
  return send;
}

export function endSend(send: Send, ok: boolean): void {
  sending.delete(send);
  if (ok) {
    lostImages.delete(send.key);
  } else {
    const text = [send.text, composerTexts.get(send.key) ?? ""].filter((t) => t).join("\n\n");
    if (text) {
      composerTexts.set(send.key, text);
    }
  }
  flushDrafts();
}

export function checkedAnswer(id: string): string[] {
  return checked.get(id) ?? [];
}

export function setCheckedAnswer(id: string, options: string[]): void {
  checked.set(id, options);
  save();
}

export function hasTextAnswer(id: string): boolean {
  return texts.has(id);
}

export function textAnswer(id: string): string | undefined {
  return texts.get(id);
}

export function setTextAnswer(id: string, text: string): void {
  texts.set(id, text);
  save();
}

export function dropTextAnswer(id: string): void {
  texts.delete(id);
  save();
}

export function clearAnswer(id: string): void {
  checked.delete(id);
  texts.delete(id);
  flushDrafts();
}