package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"time"
)

// Job mirrors the jobs table.
type Job struct {
	ID          string
	HostID      string
	Kind        string
	Status      string
	ScheduledID *string
	ActorKind   string // user|schedule|system
	ActorID     *string
	StartedAt   *time.Time
	FinishedAt  *time.Time
	ExitCode    *int
	Stats       json.RawMessage
	Error       *string
	CreatedAt   time.Time
}

// CreateJob inserts a queued job. The agent will mark it running
// when it actually starts work.
func (s *Store) CreateJob(ctx context.Context, j Job) error {
	_, err := s.db.ExecContext(ctx,
		`INSERT INTO jobs (id, host_id, kind, status, actor_kind, actor_id, created_at)
		 VALUES (?, ?, ?, 'queued', ?, ?, ?)`,
		j.ID, j.HostID, j.Kind, j.ActorKind, nullable(j.ActorID),
		j.CreatedAt.UTC().Format(time.RFC3339Nano))
	if err != nil {
		return fmt.Errorf("store: create job: %w", err)
	}
	return nil
}

// MarkJobStarted flips status to 'running' and records started_at.
func (s *Store) MarkJobStarted(ctx context.Context, id string, when time.Time) error {
	res, err := s.db.ExecContext(ctx,
		`UPDATE jobs
		 SET status = 'running', started_at = ?
		 WHERE id = ? AND status IN ('queued','running')`,
		when.UTC().Format(time.RFC3339Nano), id)
	if err != nil {
		return fmt.Errorf("store: mark started: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ErrNotFound
	}
	return nil
}

// MarkJobFinished records the terminal state.
func (s *Store) MarkJobFinished(ctx context.Context, id, status string, exitCode int, stats json.RawMessage, errMsg string, when time.Time) error {
	if len(stats) == 0 {
		stats = json.RawMessage("null")
	}
	res, err := s.db.ExecContext(ctx,
		`UPDATE jobs
		 SET status = ?, finished_at = ?, exit_code = ?, stats = ?, error = ?
		 WHERE id = ?`,
		status,
		when.UTC().Format(time.RFC3339Nano),
		exitCode, string(stats), nullableStr(errMsg), id)
	if err != nil {
		return fmt.Errorf("store: mark finished: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ErrNotFound
	}
	return nil
}

// AppendJobLog records one line of agent output. seq is the agent's
// monotonic sequence number; gaps imply lost data.
func (s *Store) AppendJobLog(ctx context.Context, jobID string, seq int64, ts time.Time, stream, payload string) error {
	_, err := s.db.ExecContext(ctx,
		`INSERT INTO job_logs (job_id, seq, ts, stream, payload) VALUES (?,?,?,?,?)`,
		jobID, seq, ts.UTC().Format(time.RFC3339Nano), stream, payload)
	if err != nil {
		return fmt.Errorf("store: append job log: %w", err)
	}
	return nil
}

// GetJob returns a job row.
func (s *Store) GetJob(ctx context.Context, id string) (*Job, error) {
	row := s.db.QueryRowContext(ctx,
		`SELECT id, host_id, kind, status, scheduled_id, actor_kind, actor_id,
		        started_at, finished_at, exit_code, stats, error, created_at
		 FROM jobs WHERE id = ?`, id)
	var (
		j           Job
		schedID     sql.NullString
		actorID     sql.NullString
		startedAt   sql.NullString
		finishedAt  sql.NullString
		exitCode    sql.NullInt64
		stats       sql.NullString
		errMsg      sql.NullString
		createdAt   string
	)
	if err := row.Scan(&j.ID, &j.HostID, &j.Kind, &j.Status, &schedID,
		&j.ActorKind, &actorID, &startedAt, &finishedAt,
		&exitCode, &stats, &errMsg, &createdAt); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, fmt.Errorf("store: scan job: %w", err)
	}
	if schedID.Valid {
		s := schedID.String
		j.ScheduledID = &s
	}
	if actorID.Valid {
		s := actorID.String
		j.ActorID = &s
	}
	if startedAt.Valid {
		t, _ := time.Parse(time.RFC3339Nano, startedAt.String)
		j.StartedAt = &t
	}
	if finishedAt.Valid {
		t, _ := time.Parse(time.RFC3339Nano, finishedAt.String)
		j.FinishedAt = &t
	}
	if exitCode.Valid {
		i := int(exitCode.Int64)
		j.ExitCode = &i
	}
	if stats.Valid && stats.String != "" {
		j.Stats = json.RawMessage(stats.String)
	}
	if errMsg.Valid {
		s := errMsg.String
		j.Error = &s
	}
	t, _ := time.Parse(time.RFC3339Nano, createdAt)
	j.CreatedAt = t
	return &j, nil
}

func nullableStr(s string) any {
	if s == "" {
		return nil
	}
	return s
}