package postgres

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"errors"
	"github.com/jackc/pgx/v5"
	"knowledge-governance/internal/jobs"
	"knowledge-governance/internal/versionhistory"
	"regexp"
	"strings"
	"time"
)

func (s *Store) EnqueueVersionHistorySync(ctx context.Context, repo, actor, target string, now time.Time) (*jobs.Job, error) {
	if strings.Count(repo, "/") != 1 || strings.TrimSpace(repo) != repo || len(repo) > 200 || actor == "" || len(actor) > 256 || target != "" && !regexp.MustCompile(`^[a-f0-9]{40}$`).MatchString(target) {
		return nil, errors.New("invalid version synchronization request")
	}
	tx, e := s.db.Begin(ctx)
	if e != nil {
		return nil, e
	}
	defer tx.Rollback(context.Background())
	if _, e = tx.Exec(ctx, `SELECT pg_advisory_xact_lock(hashtextextended($1,0))`, "version-history:"+repo); e != nil {
		return nil, e
	}
	// Retire exhausted expired owners. Terminal jobs are history, not a perpetual
	// idempotency key: a later refresh must be allowed to execute again.
	if _, e = tx.Exec(ctx, `UPDATE jobs SET state='failed',lease_owner=NULL,lease_until=NULL,updated_at=$3 WHERE type=$1 AND payload->>'repo_key'=$2 AND state='running' AND lease_until<clock_timestamp() AND attempt>=max_attempts`, versionhistory.JobType, repo, now); e != nil {
		return nil, e
	}
	var active string
	e = tx.QueryRow(ctx, `SELECT id FROM jobs WHERE type=$1 AND payload->>'repo_key'=$2 AND state IN ('pending','running','retry') ORDER BY created_at DESC,id DESC LIMIT 1`, versionhistory.JobType, repo).Scan(&active)
	if e != nil && !errors.Is(e, pgx.ErrNoRows) {
		return nil, e
	}
	if active != "" {
		job, e := scanJob(tx.QueryRow(ctx, `SELECT id,type,payload,state,priority,available_at,lease_owner,lease_until,attempt,max_attempts,last_error,idempotency_key,created_at,updated_at FROM jobs WHERE id=$1`, active))
		if e != nil {
			return nil, e
		}
		if e = tx.Commit(ctx); e != nil {
			return nil, e
		}
		return job, nil
	}
	var random [16]byte
	if _, e = rand.Read(random[:]); e != nil {
		return nil, e
	}
	id := "vh-" + hex.EncodeToString(random[:])
	payload, _ := json.Marshal(map[string]string{"repo_key": repo, "triggered_by": actor, "target_sha": target})
	job, e := NewStore(tx).Enqueue(ctx, jobs.EnqueueRequest{ID: id, Type: versionhistory.JobType, Payload: payload, AvailableAt: now, MaxAttempts: 3, IdempotencyKey: "version-history:" + repo + ":" + id}, now)
	if e != nil {
		return nil, e
	}
	if e = tx.Commit(ctx); e != nil {
		return nil, e
	}
	return job, nil
}