const fs = require("fs");
const crypto = require("crypto");
const { resolveData } = require("./paths");
const { roleOf } = require("./permissions");

const FEEDBACK_TAGS = Object.freeze([
  "good",
  "bad",
  "wrong_link",
  "hallucinated",
  "too_generic",
  "unsafe",
  "should_clarify",
  "bad_code",
  "wrong_scope"
]);

class FeedbackStore {
  constructor(options = {}) {
    this.file = options.file || resolveData("feedback", "reviews.json");
  }

  capture(input, actor) {
    const tag = FEEDBACK_TAGS.includes(input.feedback_tag) ? input.feedback_tag : null;
    if (!tag) throw new Error("Unknown feedback tag.");
    const entry = {
      id: crypto.randomUUID(),
      user_message: clean(input.user_message, 6000),
      assistant_answer: clean(input.assistant_answer, 16000),
      route_used: clean(input.route_used, 120),
      role: normalizeRole(input.role),
      origin: clean(input.origin, 80) || "webui",
      platform: clean(input.platform, 80) || "webui",
      model: clean(input.model, 200),
      timestamp: validDate(input.timestamp) || new Date().toISOString(),
      feedback_tag: tag,
      optional_correction: clean(input.optional_correction, 16000),
      status: "pending",
      submitted_by: String(actor?.id || "anonymous"),
      reviewed_by: null,
      reviewed_at: null,
      verified_by: null,
      verified_at: null,
      review_notes: "",
      export_approved: false
    };
    if (!entry.user_message || !entry.assistant_answer) {
      throw new Error("Feedback requires the user message and assistant answer.");
    }
    const store = this.read();
    store.entries.unshift(entry);
    this.write(store);
    return entry;
  }

  list({ page = 1, pageSize = 20, status = "" } = {}) {
    const filtered = this.read().entries.filter((entry) => !status || entry.status === status);
    return paginate(filtered, page, pageSize);
  }

  all() {
    return this.read().entries;
  }

  get(id) {
    return this.read().entries.find((entry) => entry.id === id) || null;
  }

  edit(id, values, actor) {
    return this.mutate(id, (entry) => ({
      ...entry,
      feedback_tag: FEEDBACK_TAGS.includes(values.feedback_tag) ? values.feedback_tag : entry.feedback_tag,
      optional_correction: clean(values.optional_correction, 16000),
      review_notes: clean(values.review_notes, 4000),
      reviewed_by: String(actor.id),
      reviewed_at: new Date().toISOString()
    }));
  }

  setStatus(id, status, actor, notes = "") {
    if (!["pending", "flagged", "verified", "approved", "rejected"].includes(status)) {
      throw new Error("Invalid review status.");
    }
    return this.mutate(id, (entry) => ({
      ...entry,
      status,
      review_notes: clean(notes, 4000) || entry.review_notes,
      reviewed_by: String(actor.id),
      reviewed_at: new Date().toISOString()
    }));
  }

  verify(id, actor, notes = "") {
    return this.mutate(id, (entry) => ({
      ...entry,
      status: entry.status === "rejected" ? "rejected" : "verified",
      review_notes: clean(notes, 4000) || entry.review_notes,
      verified_by: String(actor.id),
      verified_at: new Date().toISOString()
    }));
  }

  markExportApproved(id, actor) {
    return this.mutate(id, (entry) => ({
      ...entry,
      export_approved: true,
      reviewed_by: entry.reviewed_by || String(actor.id),
      reviewed_at: entry.reviewed_at || new Date().toISOString()
    }));
  }

  delete(id) {
    const store = this.read();
    const before = store.entries.length;
    store.entries = store.entries.filter((entry) => entry.id !== id);
    if (store.entries.length === before) return false;
    this.write(store);
    return true;
  }

  mutate(id, updater) {
    const store = this.read();
    const index = store.entries.findIndex((entry) => entry.id === id);
    if (index < 0) throw new Error("Feedback review was not found.");
    store.entries[index] = updater(store.entries[index]);
    this.write(store);
    return store.entries[index];
  }

  read() {
    try {
      const parsed = JSON.parse(fs.readFileSync(this.file, "utf8"));
      return { entries: Array.isArray(parsed.entries) ? parsed.entries : [] };
    } catch {
      return { entries: [] };
    }
  }

  write(store) {
    atomicJson(this.file, { entries: store.entries.slice(0, 5000) });
  }
}

function improvementAccess(user, config = {}) {
  const role = roleOf(user);
  const improvement = config.improvement || {};
  const trusted = role === "mod" &&
    (improvement.trusted_moderator_reviewers || []).map(String).includes(String(user?.id));
  const allowed = role === "admin" ||
    (role === "mod" && improvement.allow_moderators_to_review_responses === true);
  return {
    allowed,
    role,
    trusted,
    can_submit: allowed,
    can_flag: allowed,
    can_verify: role === "admin" || trusted,
    can_approve: role === "admin",
    can_edit: role === "admin",
    can_delete: role === "admin",
    can_implement: role === "admin",
    can_export: role === "admin",
    can_run_evals: role === "admin"
  };
}

function paginate(rows, pageValue, pageSizeValue) {
  const pageSize = Math.max(1, Math.min(100, Number.parseInt(pageSizeValue, 10) || 20));
  const pages = Math.max(1, Math.ceil(rows.length / pageSize));
  const page = Math.min(pages, Math.max(1, Number.parseInt(pageValue, 10) || 1));
  const start = (page - 1) * pageSize;
  return { entries: rows.slice(start, start + pageSize), page, pages, page_size: pageSize, total: rows.length };
}

function atomicJson(file, value) {
  const tmp = `${file}.${process.pid}.${crypto.randomBytes(4).toString("hex")}.tmp`;
  try {
    fs.writeFileSync(tmp, `${JSON.stringify(value, null, 2)}\n`);
    fs.renameSync(tmp, file);
  } finally {
    fs.rmSync(tmp, { force: true });
  }
}

function clean(value, max) {
  return String(value || "").trim().slice(0, max);
}

function normalizeRole(value) {
  return ["admin", "mod", "user"].includes(value) ? value : "user";
}

function validDate(value) {
  const date = new Date(value);
  return Number.isNaN(date.getTime()) ? null : date.toISOString();
}

module.exports = {
  FEEDBACK_TAGS,
  FeedbackStore,
  improvementAccess,
  paginate,
  atomicJson
};