package backthink

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

	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
)

// Defaults applied by normalize when a Config field is left at its zero value.
// They are compile-time constants so no magic number appears in the run path.
const (
	// defaultIntervalSec is the heartbeat period in seconds when unused
	// (15 minutes: the autonomous reflection is deliberately low-frequency).
	defaultIntervalSec = 900
	// defaultQuietStartHour and defaultQuietEndHour bound the do-not-disturb
	// window in local clock hours (00:00-07:00 vs 23:00-07:00: the window may
	// wrap midnight; two equal non-zero hours disable it).
	defaultQuietStartHour = 23
	defaultQuietEndHour   = 7
	// defaultPushLimit caps proactive pushes within defaultPushWindow to honor
	// the anti-spam rule of design/11 §6 (QQ wind control, iLink window). The
	// default drops to 1 so the owner is interrupted at most once per hour.
	defaultPushLimit  = 1
	defaultPushWindow = 60 * time.Minute
	// defaultPushCooldown is the quiet gap after a successful proactive push,
	// so a successful delivery is not immediately repeated.
	defaultPushCooldown = 30 * time.Minute
	// defaultRecentChatCooldown is the gap after the owner's last message within
	// which an autonomous push is held, so a fresh conversation is not interrupted.
	defaultRecentChatCooldown = 10 * time.Minute
	// defaultKindWindow bounds how often any single push flavor (问候/提醒/分享/
	// 关心) may repeat, so the same style cannot spam within it.
	defaultKindWindow = 2 * time.Hour
	// defaultThinkTimeout bounds a single unattended thought so it can never
	// wedge a worker goroutine.
	defaultThinkTimeout = 30 * time.Second
	// defaultSessionID scopes a think when the caller supplies none. It is the
	// loop.Run durability key, deliberately distinct from history.MainSessionID so
	// an autonomous think never collides with the live main session's checkpoint
	// store (channelbridge saves/resumes under the main id). The think still sees
	// the main conversation: LoopThinker reads history.MainSessionID for context and
	// runs under loop.OwnerEnv (design/20 §2).
	defaultSessionID = "sess-backthink"
)

// DefaultSessionID is the exported loop.Run session key for an autonomous think. It is
// exposed so the flow-viz publisher (cmd/cyrene) can also publish the backthink flow
// graph, which the backthink page and the web-chat flow page both render.
const DefaultSessionID = "sess-backthink"

// Config carries the autonomous-think tuning knobs. Zero values pick safe
// defaults via normalize, so a partially filled Config is still usable.
type Config struct {
	// Interval is the heartbeat period. When zero it is derived from
	// IntervalSec (or its default).
	Interval time.Duration
	// IntervalSec is the heartbeat period in seconds, mapped from
	// config.BackgroundConfig.IntervalSec. Ignored when Interval is set.
	IntervalSec int
	// QuietStartHour and QuietEndHour bound the do-not-disturb window in local
	// clock hours. Equal non-zero hours disable the window.
	QuietStartHour int
	QuietEndHour   int
	// PushLimit bounds proactive pushes within PushWindow. Zero uses the default.
	// Non-positive PushWindow or PushLimit disables the limit.
	PushLimit int
	// PushWindow is the sliding window over which PushLimit is enforced.
	PushWindow time.Duration
	// PushCooldown is the quiet gap after a successful proactive push before
	// another is allowed. Zero uses the default.
	PushCooldown time.Duration
	// RecentChatCooldown is the gap after the owner's last message within which an
	// autonomous push is held. Zero uses the default.
	RecentChatCooldown time.Duration
	// KindWindow bounds how often any single push flavor may repeat. Zero uses the
	// default.
	KindWindow time.Duration
	// ThinkTimeout bounds a single thinking pass. Zero uses the default.
	ThinkTimeout time.Duration
}

// ConfigFromBackground maps a config.BackgroundConfig (the source of the heartbeat
// interval, the shared quiet-hours window and the proactive-push frequency knobs)
// into a backthink.Config, leaving anything the env does not expose at its
// defaults for normalize to fill in.
func ConfigFromBackground(bg config.BackgroundConfig) Config {
	return Config{
		IntervalSec:        bg.IntervalSec,
		QuietStartHour:     bg.QuietStartHour,
		QuietEndHour:       bg.QuietEndHour,
		PushLimit:          bg.PushLimit,
		PushWindow:         time.Duration(bg.PushWindowSec) * time.Second,
		PushCooldown:       time.Duration(bg.PushCooldownSec) * time.Second,
		RecentChatCooldown: time.Duration(bg.RecentChatCooldownSec) * time.Second,
		KindWindow:         time.Duration(bg.KindWindowSec) * time.Second,
	}
}

// normalize fills a Config's zero fields with safe defaults.
func normalize(cfg Config) Config {
	if cfg.IntervalSec <= 0 {
		cfg.IntervalSec = defaultIntervalSec
	}
	if cfg.Interval <= 0 {
		cfg.Interval = time.Duration(cfg.IntervalSec) * time.Second
	}
	if cfg.QuietStartHour == 0 && cfg.QuietEndHour == 0 {
		cfg.QuietStartHour = defaultQuietStartHour
		cfg.QuietEndHour = defaultQuietEndHour
	}
	if cfg.PushLimit <= 0 {
		cfg.PushLimit = defaultPushLimit
	}
	if cfg.PushWindow <= 0 {
		cfg.PushWindow = defaultPushWindow
	}
	if cfg.PushCooldown <= 0 {
		cfg.PushCooldown = defaultPushCooldown
	}
	if cfg.RecentChatCooldown <= 0 {
		cfg.RecentChatCooldown = defaultRecentChatCooldown
	}
	if cfg.KindWindow <= 0 {
		cfg.KindWindow = defaultKindWindow
	}
	if cfg.ThinkTimeout <= 0 {
		cfg.ThinkTimeout = defaultThinkTimeout
	}
	return cfg
}

// quietHoursLabel renders the do-not-disturb window for logs.
func quietHoursLabel(start, end int) string {
	return fmt.Sprintf("%02d:00-%02d:00", start, end)
}

// baseLog returns l when non-nil, otherwise a discard logger, so New always has a
// safe logger to tag.
func baseLog(l *slog.Logger) *slog.Logger {
	if l != nil {
		return l
	}
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}