// Package jobs owns generation-job state, ownership, idempotency, and worker
// coordination independently of HTTP, provider, storage, and billing adapters.
package jobs

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"sort"
	"strings"
	"time"
)

type Status string

const (
	StatusQueued    Status = "queued"
	StatusRunning   Status = "running"
	StatusSucceeded Status = "succeeded"
	StatusFailed    Status = "failed"
	StatusExpired   Status = "expired"
	StatusCancelled Status = "cancelled"
)

func (status Status) Terminal() bool {
	return status == StatusSucceeded || status == StatusFailed || status == StatusExpired || status == StatusCancelled
}

func (status Status) Valid() bool {
	return status == StatusQueued || status == StatusRunning || status.Terminal()
}

type Job struct {
	ID                        string          `json:"id"`
	OwnerID                   string          `json:"ownerId"`
	ExternalClientID          string          `json:"externalClientId,omitempty"`
	Capability                string          `json:"capability"`
	Provider                  string          `json:"provider"`
	ReqKey                    string          `json:"reqKey"`
	Status                    Status          `json:"status"`
	Prompt                    string          `json:"prompt,omitempty"`
	InputAssetIDs             []string        `json:"inputAssetIds"`
	InputURLs                 []string        `json:"inputUrls"`
	OutputAssetIDs            []string        `json:"outputAssetIds"`
	ProviderTaskID            string          `json:"providerTaskId,omitempty"`
	ProviderDispatchStartedAt *time.Time      `json:"providerDispatchStartedAt,omitempty"`
	RequestPayload            json.RawMessage `json:"requestPayload"`
	ResponsePayload           json.RawMessage `json:"responsePayload,omitempty"`
	Error                     *JobError       `json:"error,omitempty"`
	RetryOf                   string          `json:"retryOf,omitempty"`
	IdempotencyKey            string          `json:"idempotencyKey,omitempty"`
	IdempotencyFingerprint    string          `json:"idempotencyFingerprint,omitempty"`
	Priority                  int             `json:"priority,omitempty"`
	Attempts                  int             `json:"attempts,omitempty"`
	MaxAttempts               int             `json:"maxAttempts,omitempty"`
	ScheduledAt               time.Time       `json:"scheduledAt,omitempty"`
	LockedAt                  *time.Time      `json:"lockedAt,omitempty"`
	LockedBy                  string          `json:"lockedBy,omitempty"`
	StartedAt                 *time.Time      `json:"startedAt,omitempty"`
	CompletedAt               *time.Time      `json:"completedAt,omitempty"`
	DispatchReadyAt           *time.Time      `json:"dispatchReadyAt,omitempty"`
	FinalizedAt               *time.Time      `json:"finalizedAt,omitempty"`
	WebhookURL                string          `json:"webhookUrl,omitempty"`
	WebhookAttempts           int             `json:"webhookAttempts,omitempty"`
	WebhookLastStatus         json.RawMessage `json:"webhookLastStatus,omitempty"`
	UsageContext              json.RawMessage `json:"usageContext,omitempty"`
	Billing                   json.RawMessage `json:"billing,omitempty"`
	CreatedAt                 time.Time       `json:"createdAt"`
	UpdatedAt                 time.Time       `json:"updatedAt"`
}

type JobError struct {
	Code      any    `json:"code,omitempty"`
	Message   string `json:"message"`
	Retryable bool   `json:"retryable,omitempty"`
}

type Scope struct {
	OwnerID          string
	ExternalClientID string
}

func (scope Scope) Owns(job Job) bool {
	if scope.OwnerID == "" || job.OwnerID != scope.OwnerID {
		return false
	}
	return scope.ExternalClientID == "" || job.ExternalClientID == scope.ExternalClientID
}

type ErrorKind string

const (
	ErrorInvalid  ErrorKind = "invalid"
	ErrorNotFound ErrorKind = "not_found"
	ErrorConflict ErrorKind = "conflict"
)

type Error struct {
	Kind    ErrorKind
	Status  int
	Message string
}

func (err *Error) Error() string { return err.Message }

var ErrUniqueIdempotency = errors.New("generation job idempotency key already exists")
var ErrTransitionConflict = errors.New("generation job transition conflict")

type ListFilter struct {
	Scope      Scope
	Status     Status
	Capability string
	Limit      int
	Before     *time.Time
}

type CreateCommand struct {
	Job             Job
	IdempotencyBody map[string]any
	// HoldDispatch keeps a newly persisted job invisible to workers until an
	// external prerequisite (currently the idempotent wallet charge) is durable.
	HoldDispatch bool
}

func NormalizePriority(value int) int {
	if value < -100 {
		return -100
	}
	if value > 100 {
		return 100
	}
	return value
}

func NormalizePublicLimit(value int) int {
	if value == 0 {
		return 50
	}
	if value < 1 {
		return 1
	}
	if value > 200 {
		return 200
	}
	return value
}

// Fingerprint excludes the compatibility body key idempotencyKey, recursively
// sorts object keys, preserves array order, and hashes the exact stable JSON.
func Fingerprint(body map[string]any) (string, error) {
	source := make(map[string]any, len(body))
	for key, value := range body {
		if key != "idempotencyKey" {
			source[key] = value
		}
	}
	stable, err := stableJSON(source)
	if err != nil {
		return "", err
	}
	sum := sha256.Sum256(stable)
	return hex.EncodeToString(sum[:]), nil
}

func stableJSON(value any) ([]byte, error) {
	switch typed := value.(type) {
	case map[string]any:
		keys := make([]string, 0, len(typed))
		for key := range typed {
			keys = append(keys, key)
		}
		sort.Strings(keys)
		var output strings.Builder
		output.WriteByte('{')
		for index, key := range keys {
			if index > 0 {
				output.WriteByte(',')
			}
			encodedKey, _ := json.Marshal(key)
			encodedValue, err := stableJSON(typed[key])
			if err != nil {
				return nil, err
			}
			output.Write(encodedKey)
			output.WriteByte(':')
			output.Write(encodedValue)
		}
		output.WriteByte('}')
		return []byte(output.String()), nil
	case []any:
		var output strings.Builder
		output.WriteByte('[')
		for index, item := range typed {
			if index > 0 {
				output.WriteByte(',')
			}
			encoded, err := stableJSON(item)
			if err != nil {
				return nil, err
			}
			output.Write(encoded)
		}
		output.WriteByte(']')
		return []byte(output.String()), nil
	default:
		encoded, err := json.Marshal(value)
		if err != nil {
			return nil, fmt.Errorf("encode idempotency fingerprint: %w", err)
		}
		return encoded, nil
	}
}