// Package automations implements the Cyrene v2 automation engine and reminder
// scheduler (DevDocs/design/04-运行时.md §8.5). It is the "how she does things on
// her own" layer: schedules and event rules fire a named action, the action runs
// (either a plain function, a registered tool, or a prompt through the AI
// loop/agent pipeline), and every outcome is published back to the bus so upper
// layers can react or push notifications.
//
// The package is split into five files:
//
//   - automations.go — shared types: Config, Deps, the Pipeline abstraction, the
//     published Result and the sentinel errors.
//   - scheduler.go  — the cron-driven Scheduler (robfig/cron/v3).
//   - rule.go       — the Rule model and the event-driven Engine.
//   - action.go     — the Action interface plus func/tool/AI implementations.
//   - reminder.go   — the time-based ReminderStore.
//   - service.go    — the Service that composes the three for lifecycle control.
//
// Execution model: every trigger (cron fire, event match, reminder due) resolves
// to the same runAction, which executes the Action under an optional deadline and
// publishes a Result to the "automation.result" subject. This keeps reporting and
// logging consistent across all trigger kinds (DevDocs/design/04-运行时.md §8.5:
// task output returns to the message queue/agent).
//
// Identity and capability boundaries (Devedocs global red lines): automation
// never decides who is allowed to do anything. It only fires named actions;
// authorization stays in the channel/policy layer.
package automations

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/bus"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/logger"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/loop"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
)

// Bus subjects published by the automations engine. Upper layers subscribe to
// these to observe outcomes or push notifications.
const (
	// SubjectResult is the subject every executed automation publishes its
	// Result to.
	SubjectResult = "automation.result"
	// SubjectTrigger is the subject a due Reminder is published to. Upper layers
	// subscribe to it to surface the reminder to the user.
	SubjectTrigger = "reminder.trigger"
)

// Sentinel errors returned by this package. Use errors.Is to test for them.
var (
	// ErrNilBus is returned when a constructor receives a nil bus.
	ErrNilBus = errors.New("automations: nil bus")
	// ErrNilAction is returned when an action is nil or unnamed.
	ErrNilAction = errors.New("automations: nil action")
	// ErrInvalidRule is returned when a rule is malformed.
	ErrInvalidRule = errors.New("automations: invalid rule")
	// ErrInvalidCron is returned when a cron expression fails to parse.
	ErrInvalidCron = errors.New("automations: invalid cron expression")
	// ErrNotFound is returned when a rule or reminder is missing.
	ErrNotFound = errors.New("automations: not found")
	// ErrDuplicate is returned when a rule or reminder id is already registered.
	ErrDuplicate = errors.New("automations: already exists")
	// ErrNoPipeline is returned when an AI action is built without a pipeline.
	ErrNoPipeline = errors.New("automations: no AI pipeline configured")
)

// Config configures the automations engine.
type Config struct {
	// Location is the timezone used for cron schedules and reminder firing. Nil
	// uses time.Local.
	Location *time.Location
	// WithSeconds enables 6-field cron specs (with a leading seconds field) in
	// addition to the standard 5-field format.
	WithSeconds bool
	// ActionTimeout bounds a single action execution. Non-positive disables the
	// deadline.
	ActionTimeout time.Duration
	// ReminderInterval is how often the reminder loop polls for due reminders.
	// Non-positive selects defaultReminderInterval.
	ReminderInterval time.Duration
}

// Deps is the injected dependency set for the automations engine.
type Deps struct {
	// Bus is the in-process event bus. Required.
	Bus bus.Bus
	// Loop is the AI pipeline (the agent loop). When set, an AI action runs
	// through it. Agent is used only when Loop is nil.
	Loop *loop.Loop
	// Agent is the single-step agent, used as the AI pipeline when Loop is nil.
	Agent *agent.Agent
	// Log is the base logger. A nil logger is replaced with a discard logger
	// tagged with source "services/automations".
	Log *slog.Logger
	// Now supplies the current time for reminders. Nil uses time.Now.
	Now func() time.Time
}

// Pipeline is the AI-execution surface an automation action runs through. It is
// satisfied by *loop.Loop directly, so a real pipeline can be injected without
// an adapter. Tests inject a fake to observe the prompt and return canned text.
type Pipeline interface {
	Run(ctx context.Context, sessionID string, messages []model.Message) (*loop.Result, error)
}

// AgentPipeline adapts an *agent.Agent to Pipeline by running a single step and
// returning its text as the result. It is used when only an agent (not a full
// loop) is injected.
type AgentPipeline struct {
	Agent *agent.Agent
}

// Run runs one agent step and returns its text as the loop-style Result.
func (a *AgentPipeline) Run(ctx context.Context, sessionID string, messages []model.Message) (*loop.Result, error) {
	if a.Agent == nil {
		return nil, fmt.Errorf("automations: agent pipeline: %w", ErrNoPipeline)
	}
	sr, err := a.Agent.RunStep(ctx, sessionID, messages)
	if err != nil {
		return nil, fmt.Errorf("automations: agent pipeline run: %w", err)
	}
	return &loop.Result{Text: sr.Text, StopReason: sr.StopReason, Steps: 1}, nil
}

// pipeline returns the resolved AI pipeline from deps, or nil when neither a
// loop nor an agent is configured.
func (d Deps) pipeline() Pipeline {
	if d.Loop != nil {
		return d.Loop
	}
	if d.Agent != nil {
		return &AgentPipeline{Agent: d.Agent}
	}
	return nil
}

// AutomationRecord is the read-only summary of one automation or reminder,
// returned by Service.List for the admin panel. Kind is "cron", "event" or
// "reminder"; Cron carries the cron expression for the cron kind; LastRun and
// NextRun are zero times when the value is unknown (typically before Start).
type AutomationRecord struct {
	ID      string
	Name    string
	Kind    string
	Cron    string
	Enabled bool
	LastRun time.Time
	NextRun time.Time
}

// Result is the structured outcome of an executed automation, published to
// SubjectResult. Upper layers subscribe to it to react or push notifications.
type Result struct {
	// Kind classifies the trigger: "schedule", "event" or "reminder".
	Kind string `json:"kind"`
	// RuleID identifies the schedule/rule/reminder that fired.
	RuleID string `json:"rule_id"`
	// Action is the action name that ran.
	Action string `json:"action"`
	// Payload is the trigger payload (nil for a cron fire).
	Payload any `json:"payload"`
	// Output is the action's returned value, or nil on error.
	Output any `json:"output"`
	// Error carries the action's error message when the run failed.
	Error string `json:"error,omitempty"`
}

// sourcedLog returns a base logger tagged with the module source
// "services/automations", replacing a nil logger with a discard one so callers
// can always log safely.
func sourcedLog(l *slog.Logger) *slog.Logger {
	if l == nil {
		l = slog.New(slog.NewTextHandler(io.Discard, nil))
	}
	return logger.WithSource(l, "services/automations")
}

// resolveNow returns f when non-nil, otherwise time.Now.
func resolveNow(f func() time.Time) func() time.Time {
	if f == nil {
		return time.Now
	}
	return f
}

// payloadKind 返回触发 payload 的 Go 类型名，用于日志里替代 payload 本身。
// 类型名是代码事实（*gateway.ChatEvent 之类），正文才是敏感物 —— 排查「这条路
// 上跑的是什么消息」靠类型名与体积够了，不需要内容。
//
// 它**不**调用 payload 的 String()/Error()：那正是把正文请进日志的常见口子。
func payloadKind(payload any) string {
	if payload == nil {
		return "nil"
	}
	return fmt.Sprintf("%T", payload)
}