package store

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"time"
)

// SystemJobTenantID owns global maintenance jobs outside user tenant scope.
const SystemJobTenantID = "00000000-0000-0000-0000-000000000000"

// JobRequestHash identifies the immutable requested operation, excluding result metadata.
func JobRequestHash(in JobEnqueue) (string, error) {
	meta := in.Meta
	if in.Request != nil {
		meta = in.Request
	}
	b, err := json.Marshal(struct {
		Kind     string         `json:"kind"`
		ModuleID *string        `json:"module_id"`
		Meta     map[string]any `json:"meta"`
	}{in.Kind, in.ModuleID, meta})
	if err != nil {
		return "", err
	}
	h := sha256.Sum256(b)
	return hex.EncodeToString(h[:]), nil
}

var (
	ErrJobNotFound  = errors.New("store: job not found")
	ErrJobConflict  = errors.New("store: idempotency key conflicts with another request")
	ErrJobQueueFull = errors.New("store: job queue is full")
	ErrJobLeaseLost = errors.New("store: job lease lost")
)

// JobRecord is the shared, tenant-scoped job lifecycle record.
type JobRecord struct {
	RequestHash                string
	ID, TenantID, Kind, Status string
	IdempotencyKey, ModuleID   *string
	Meta                       map[string]any
	CreatedAt                  time.Time
	StartedAt, FinishedAt      *time.Time
	LeaseUntil                 *time.Time
	Error                      *string
	OwnerID                    string
	FencingToken               int64
	RequestSequence            int64
	Attempt                    int
	CancelRequested            bool
}

// JobEnqueue is the immutable request used for idempotent insertion.
type JobEnqueue struct {
	TenantID, Kind           string
	IdempotencyKey, ModuleID *string
	Meta                     map[string]any
	// Request optionally supplies the original selector before dynamic resolution.
	Request map[string]any
}

// JobQueue provides durable operations; PostgreSQL is authoritative in production.
type JobQueue interface {
	CountJobsByStatus(context.Context) (map[string]int64, error)
	FindJobByIdempotencyKey(context.Context, string, string) (JobRecord, error)
	EnqueueJob(context.Context, JobEnqueue) (JobRecord, bool, error)
	ClaimJobs(context.Context, string, int, time.Duration) ([]JobRecord, error)
	// ReapExpiredJobs marks orphaned cancellations and exhausted retries as terminal.
	// Production callers run it about every 15 seconds, not on every claim.
	ReapExpiredJobs(context.Context) error
	HeartbeatJob(context.Context, string, string, int64, time.Duration) (bool, error)
	CheckpointJob(context.Context, JobRecord) error
	FinishJob(context.Context, JobRecord) error
	ReleaseJob(context.Context, string, string, int64) error
	GetJob(context.Context, string, string) (JobRecord, error)
	ListJobs(context.Context, string, string, string, string, int) ([]JobRecord, string, bool, error)
	CancelJob(context.Context, string, string) (JobRecord, error)
	RetryJob(context.Context, string, string) (JobRecord, error)
}