import { DatabaseSync } from 'node:sqlite';
import { mkdirSync, chmodSync } from 'node:fs';
import path from 'node:path';
import { randomUUID, createHash } from 'node:crypto';

const hash = value => createHash('sha256').update(value).digest('hex');
export function briefWeekKey(now = new Date()) {
  const date = new Date(now.getTime() + 3 * 3600000);
  date.setUTCDate(date.getUTCDate() - (date.getUTCDay()+6)%7);
  return date.toISOString().slice(0,10);
}

/** A claimed message is never blindly replayed after an interrupted provider call. */
export function createBriefOutbox(directory) {
  function transaction(work) {
    mkdirSync(directory,{recursive:true,mode:0o700});
    const file=path.join(directory,'brief.sqlite');
    const db = new DatabaseSync(file);
    try {
      chmodSync(file,0o600);
      db.exec(`PRAGMA busy_timeout=5000; PRAGMA journal_mode=WAL; PRAGMA synchronous=FULL;
        CREATE TABLE IF NOT EXISTS brief_batches(id TEXT PRIMARY KEY,week TEXT NOT NULL,email TEXT NOT NULL,manifest TEXT NOT NULL);
        CREATE TABLE IF NOT EXISTS brief_messages(batch TEXT NOT NULL,position INTEGER NOT NULL,state TEXT NOT NULL,lease TEXT,lease_until INTEGER,receipt TEXT,error TEXT,PRIMARY KEY(batch,position));`);
      db.exec('BEGIN IMMEDIATE');
      const result=work(db);
      db.exec('COMMIT');
      return result;
    } catch(error) { try { db.exec('ROLLBACK'); } catch {} throw error; }
    finally { db.close(); }
  }
  return {
    prepare(week,email,messages) {
      const id=hash(JSON.stringify([week,email])),manifest=JSON.stringify(messages);
      return transaction(db=>{
        const row=db.prepare('SELECT manifest FROM brief_batches WHERE id=?').get(id);
        if(row) {
          const changed=row.manifest!==manifest;
          if(changed) db.prepare("UPDATE brief_messages SET state='uncertain',error=? WHERE batch=? AND state='pending'")
            .run('Haftalık özet içeriği veya alıcı kanalı değişti; yeniden gönderim öncesi inceleme gerekli.',id);
          return {id,changed};
        }
        db.prepare('INSERT INTO brief_batches VALUES (?,?,?,?)').run(id,week,email,manifest);
        const insert=db.prepare("INSERT INTO brief_messages(batch,position,state) VALUES (?,?,'pending')");
        messages.forEach((_,i)=>insert.run(id,i));
        return {id,changed:false};
      });
    },
    claim(batch,position,clock=Date.now()) {
      return transaction(db=>{
        const row=db.prepare('SELECT * FROM brief_messages WHERE batch=? AND position=?').get(batch,position);
        if(!row)throw new Error('Özet teslimat kaydı bulunamadı.');
        if(row.state==='accepted')return {state:'accepted'};
        if(row.state==='uncertain')return {state:'uncertain'};
        if(row.state==='sending') {
          if(row.lease_until>clock)return {state:'busy'};
          db.prepare("UPDATE brief_messages SET state='uncertain',error=? WHERE batch=? AND position=?").run('Kesintiye uğrayan gönderim; sağlayıcı kaydı incelenmeli.',batch,position);
          return {state:'uncertain'};
        }
        const lease=randomUUID();
        db.prepare("UPDATE brief_messages SET state='sending',lease=?,lease_until=? WHERE batch=? AND position=?").run(lease,clock+120000,batch,position);
        return {state:'sending',batch,position,lease};
      });
    },
    accept(claim,receipt) {
      if(typeof receipt!=='string'||!receipt.trim())throw new Error('Gönderim kabul kaydı gerekli.');
      return transaction(db=>{
        const result=db.prepare("UPDATE brief_messages SET state='accepted',receipt=?,error=NULL WHERE batch=? AND position=? AND lease=? AND state='sending'")
          .run(receipt,claim.batch,claim.position,claim.lease);
        if(result.changes!==1)throw new Error('Özet gönderim kaydı değişti.');
      });
    },
    hold(claim,error) {
      return transaction(db=>db.prepare("UPDATE brief_messages SET state='uncertain',error=? WHERE batch=? AND position=? AND lease=? AND state='sending'")
        .run(String(error?.message || error),claim.batch,claim.position,claim.lease).changes===1);
    },
    inspect() {
      return transaction(db=>db.prepare('SELECT b.week,b.email,m.* FROM brief_messages m JOIN brief_batches b ON b.id=m.batch ORDER BY b.week DESC,b.email,m.position').all());
    },
  };
}