package models

import (
	"time"

	"gorm.io/datatypes"
	"gorm.io/gorm/clause"

	"rsgit.ru/rsmon/rsmon/app/models/concerns"
)

// Task kinds stored in the tasks.kind column. The plan (docs/plans/worker-notifier-mvp.md
// section 4.1) reserves the same enum for checks and notifications; this phase only
// emits notification rows but the enum is shared so the selector can stay a single
// function.
const (
	TaskKindNotification = "notification"
	TaskKindCheck        = "check"
	TaskKindServerMetric = "server_metric"
)

// Task states for the durable task envelope.
const (
	TaskStateQueued      = "queued"
	TaskStateLeased      = "leased"
	TaskStateSucceeded   = "succeeded"
	TaskStateFailedRetry = "failed_retry"
	TaskStateFailedPerm  = "failed_perm"
	TaskStateDead        = "dead"
)

// Notification result statuses reported by the worker (mirrors the wire enum so the
// result handler can decode without re-typing the constants).
const (
	NotificationResultDelivered = "delivered"
	NotificationResultRetryable = "retryable"
	NotificationResultPermanent = "permanent"
	NotificationResultPartial   = "partial"
)

// SkipLockedClause is the SELECT ... FOR UPDATE SKIP LOCKED clause used by
// every worker-pool selector (checks in check_jobs.ChecksForWorker and
// tasks in task_selector.TasksForWorker / TasksForWorkerNotification).
// Sharing the value keeps the SQL identical across selectors so goconst
// does not flag the literal, and a future change (e.g. NOWAIT) only has
// to touch one place.
var SkipLockedClause = clause.Locking{Strength: "UPDATE", Options: "SKIP LOCKED"}

// Task is the durable envelope for both check and notification work executed by the
// distributed worker pool. Selection uses FOR UPDATE SKIP LOCKED per worker poll so
// a single primary key or sequence never becomes the bottleneck.
//
// Phase 1 (this commit) only emits notification tasks. The `kind` discriminator and
// capability filters are designed to accept checks in phase 2 without a schema change.
type Task struct {
	concerns.Model

	JobID     string `gorm:"uniqueIndex;size:64" json:"job_id"`
	Kind      string `gorm:"size:32;index" json:"kind"`
	State     string `gorm:"size:32;index" json:"state"`
	LastError string `gorm:"type:text" json:"last_error"`

	// Tenancy + audit anchor. AccountID is required for the capability match in
	// TasksForWorker; monitor_id / message_id / contact_id are denormalized for
	// fast admin queries.
	AccountID int64  `gorm:"index" json:"account_id"`
	MonitorID *int64 `gorm:"index" json:"monitor_id,omitempty"`
	CheckID   *int64 `json:"check_id,omitempty"`
	MessageID *int64 `json:"message_id,omitempty"`
	ContactID *int64 `json:"contact_id,omitempty"`

	// Payload is the kind-specific blob the worker needs to execute. For
	// notifications the producer pre-renders subject/body so the worker does not
	// need templating context (see RenderNotificationContent in internal/notifier).
	Payload datatypes.JSON `gorm:"type:jsonb" json:"payload"`

	// Scheduling + retry envelope. NotBefore is set to NOW() by the producer and
	// bumped by the result handler on retryable failures. Deadline is a soft cap
	// the selector can use to skip stale tasks.
	NotBefore time.Time  `json:"not_before"`
	Deadline  *time.Time `json:"deadline,omitempty"`

	// LeaseOwner + LeaseExpiresAt are owned by the selector while the task is
	// in state=leased. The reaper clears them when the lease expires.
	LeaseOwner     string     `gorm:"size:128" json:"lease_owner"`
	LeaseToken     string     `gorm:"size:64" json:"-"`
	LeaseExpiresAt *time.Time `json:"lease_expires_at,omitempty"`

	Attempts    int `json:"attempts"`
	MaxAttempts int `json:"max_attempts"`

	// IdempotencyKey is unique per logical event so a retry of the producer's
	// enqueue never produces a second Task row. See EnqueueNotificationTask.
	IdempotencyKey string `gorm:"uniqueIndex;size:255" json:"idempotency_key"`

	// Result holds the most recent worker result body (NotificationResultReport or
	// CheckResultReport shape, depending on Kind). It is JSONB so the admin UI can
	// pretty-print without a separate result table for transient lookups.
	Result      datatypes.JSON `gorm:"type:jsonb" json:"result"`
	SucceededAt *time.Time     `json:"succeeded_at,omitempty"`

	concerns.Timestamped
}

// TaskReplay records the single operator-initiated replay of a dead task.
// OriginalTaskID is unique, making repeated clicks/API retries idempotent.
type TaskReplay struct {
	concerns.Model
	OriginalTaskID int64 `gorm:"uniqueIndex" json:"original_task_id"`
	RequeuedTaskID int64 `gorm:"uniqueIndex" json:"requeued_task_id"`
	OperatorUserID int64 `gorm:"index" json:"operator_user_id"`
	concerns.Timestamped
}

// TableName overrides the default table name so pluralization stays consistent
// with the rest of the schema (tasks, not "task" or "taskses").
func (Task) TableName() string {
	return "tasks"
}

// NotificationDelivery is the per-attempt audit row required by section 7.5 of the
// plan ("Audit rows: each successful or failed delivery writes a row in a new
// notification_deliveries table"). The result handler appends one row per result
// frame, which lets support answer "did the customer ever get this alert" without
// scanning application logs.
type NotificationDelivery struct {
	concerns.Model

	MessageID int64  `gorm:"index" json:"message_id"`
	WorkerID  string `gorm:"size:128;index" json:"worker_id"`
	TaskID    int64  `gorm:"index" json:"task_id"`

	Status string `gorm:"size:32" json:"status"`
	Error  string `gorm:"type:text" json:"error"`

	DurationMs       int    `json:"duration_ms"`
	ProviderResponse string `gorm:"type:text" json:"provider_response"`

	concerns.Timestamped
}

// TableName mirrors the plan's preferred lowercase plural.
func (NotificationDelivery) TableName() string {
	return "notification_deliveries"
}