// Package clock is an example skill giving any agent reliable time
// awareness: a current-time tool (models cannot know "now") and a timezone
// conversion tool, with an injectable clock for tests.
package clock

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"gitea.stevedudenhoeffer.com/steve/majordomo/llm"
	"gitea.stevedudenhoeffer.com/steve/majordomo/skill"
)

// Option configures the skill.
type Option func(*config)

type config struct {
	now func() time.Time
}

// WithClock injects the time source (tests).
func WithClock(now func() time.Time) Option {
	return func(c *config) { c.now = now }
}

// New builds the clock skill.
func New(opts ...Option) *skill.Skill {
	cfg := config{now: time.Now}
	for _, opt := range opts {
		opt(&cfg)
	}

	nowTool := llm.Tool{
		Name:        "time_now",
		Description: "Get the current date and time. Use whenever the user's request depends on today's date or the current time.",
		Parameters: json.RawMessage(`{
			"type": "object",
			"properties": {
				"timezone": {"type": "string", "description": "IANA timezone like America/New_York; defaults to UTC"}
			}
		}`),
		Handler: func(_ context.Context, args json.RawMessage) (any, error) {
			var p struct {
				Timezone string `json:"timezone"`
			}
			if err := json.Unmarshal(args, &p); err != nil {
				return nil, fmt.Errorf("bad arguments: %w", err)
			}
			loc := time.UTC
			if p.Timezone != "" {
				var err error
				if loc, err = time.LoadLocation(p.Timezone); err != nil {
					return nil, fmt.Errorf("unknown timezone %q", p.Timezone)
				}
			}
			t := cfg.now().In(loc)
			return map[string]string{
				"rfc3339": t.Format(time.RFC3339),
				"weekday": t.Weekday().String(),
				"human":   t.Format("Monday, January 2, 2006 at 15:04 MST"),
			}, nil
		},
	}

	convertTool := llm.Tool{
		Name:        "time_convert",
		Description: "Convert an RFC3339 timestamp to another timezone.",
		Parameters: json.RawMessage(`{
			"type": "object",
			"properties": {
				"time": {"type": "string", "description": "RFC3339 timestamp"},
				"timezone": {"type": "string", "description": "target IANA timezone"}
			},
			"required": ["time", "timezone"]
		}`),
		Handler: func(_ context.Context, args json.RawMessage) (any, error) {
			var p struct {
				Time     string `json:"time"`
				Timezone string `json:"timezone"`
			}
			if err := json.Unmarshal(args, &p); err != nil {
				return nil, fmt.Errorf("bad arguments: %w", err)
			}
			t, err := time.Parse(time.RFC3339, p.Time)
			if err != nil {
				return nil, fmt.Errorf("unparseable time %q: %w", p.Time, err)
			}
			loc, err := time.LoadLocation(p.Timezone)
			if err != nil {
				return nil, fmt.Errorf("unknown timezone %q", p.Timezone)
			}
			return map[string]string{"rfc3339": t.In(loc).Format(time.RFC3339)}, nil
		},
	}

	return skill.New("clock",
		skill.WithInstructions("You have time tools. Never guess the current date or time — call time_now. Use time_convert for timezone math."),
		skill.WithTools(nowTool, convertTool),
	)
}