package tools

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"

	"github.com/nextlevelbuilder/goclaw/internal/bus"
)

var ErrAnnounceQueueDrainTimeout = errors.New("announce_queue_drain_timeout")

// AnnounceQueueItem represents a single subagent result waiting to be announced.
type AnnounceQueueItem struct {
	SubagentID       string
	CompletionID     uuid.UUID
	DurablyPersisted bool
	ParentTaskID     string
	Depth            int
	Label            string
	Status           string // "completed", "failed", "cancelled"
	Result           string
	Media            []bus.MediaFile // media files from tool results
	Runtime          time.Duration
	Iterations       int
	InputTokens      int64
	OutputTokens     int64
}

// AnnounceMetadata carries origin info for routing the batched announce.
type AnnounceMetadata struct {
	OriginChannel    string
	OriginChatID     string
	OriginPeerKind   string
	OriginLocalKey   string // composite key with topic/thread suffix for routing
	OriginUserID     string
	OriginSenderID   string    // real acting sender; preserves permission attribution through re-ingress (#915)
	OriginRole       string    // caller's RBAC role; bypasses per-user grants for admin/operator/owner (#915)
	OriginSessionKey string    // exact parent session key (WS uses non-standard format)
	OriginTenantID   uuid.UUID // parent tenant for announce routing
	RootAgentID      uuid.UUID
	ParentAgent      string
	OriginTraceID    string // parent trace UUID for announce linking
	OriginRootSpanID string // parent agent's root span UUID
}

// AnnounceQueue batches subagent announces per session with debounce,
// matching TS subagent-announce-queue.ts "collect" mode.
type AnnounceQueue struct {
	mu       sync.Mutex
	queues   map[string]*sessionQueue // session key → queue
	debounce time.Duration            // default 1000ms
	cap      int                      // max items per session before immediate drain (default 20)
	onDrain  func(sessionKey string, items []AnnounceQueueItem, meta AnnounceMetadata)
	closed   bool
	drainWG  sync.WaitGroup
}

type sessionQueue struct {
	items []AnnounceQueueItem
	timer *time.Timer
	meta  AnnounceMetadata
}

// NewAnnounceQueue creates an announce queue with the given debounce and drain callback.
func NewAnnounceQueue(
	debounceMs int,
	cap int,
	onDrain func(sessionKey string, items []AnnounceQueueItem, meta AnnounceMetadata),
) *AnnounceQueue {
	if debounceMs <= 0 {
		debounceMs = 1000 // TS default
	}
	if cap <= 0 {
		cap = 20 // TS default
	}
	return &AnnounceQueue{
		queues:   make(map[string]*sessionQueue),
		debounce: time.Duration(debounceMs) * time.Millisecond,
		cap:      cap,
		onDrain:  onDrain,
	}
}

// Enqueue adds an announce item to the session queue.
// Resets the debounce timer. Drains immediately if cap is reached.
func (aq *AnnounceQueue) Enqueue(sessionKey string, item AnnounceQueueItem, meta AnnounceMetadata) {
	aq.mu.Lock()
	defer aq.mu.Unlock()
	if aq.closed {
		return
	}

	sq, ok := aq.queues[sessionKey]
	if !ok {
		sq = &sessionQueue{meta: meta}
		aq.queues[sessionKey] = sq
	}

	sq.items = append(sq.items, item)

	// Drain immediately if cap reached
	if len(sq.items) >= aq.cap {
		if sq.timer != nil {
			sq.timer.Stop()
		}
		items := sq.items
		sqMeta := sq.meta
		delete(aq.queues, sessionKey)
		aq.startDrainLocked(sessionKey, items, sqMeta)
		return
	}

	// Reset debounce timer
	if sq.timer != nil {
		sq.timer.Stop()
	}
	sq.timer = time.AfterFunc(aq.debounce, func() {
		aq.mu.Lock()
		sq, ok := aq.queues[sessionKey]
		if !ok {
			aq.mu.Unlock()
			return
		}
		items := sq.items
		sqMeta := sq.meta
		delete(aq.queues, sessionKey)
		aq.startDrainLocked(sessionKey, items, sqMeta)
		aq.mu.Unlock()
	})
}

func (aq *AnnounceQueue) startDrainLocked(
	sessionKey string,
	items []AnnounceQueueItem,
	meta AnnounceMetadata,
) {
	if aq.closed {
		return
	}
	aq.drainWG.Add(1)
	go func() {
		defer aq.drainWG.Done()
		aq.drain(sessionKey, items, meta)
	}()
}

// CloseContext closes intake, drops pending debounce batches, and waits for any
// drain callback that already started. Dropping pending parent-resume messages
// during process shutdown avoids starting new agent runs against dependencies
// that are being torn down; task terminal state remains durable.
func (aq *AnnounceQueue) CloseContext(ctx context.Context) error {
	if aq == nil {
		return nil
	}
	if ctx == nil {
		ctx = context.Background()
	}
	aq.mu.Lock()
	if !aq.closed {
		aq.closed = true
		for _, queue := range aq.queues {
			if queue.timer != nil {
				queue.timer.Stop()
			}
		}
		clear(aq.queues)
	}
	aq.mu.Unlock()

	done := make(chan struct{})
	go func() {
		aq.drainWG.Wait()
		close(done)
	}()
	select {
	case <-done:
		return nil
	case <-ctx.Done():
		return fmt.Errorf("%w: %v", ErrAnnounceQueueDrainTimeout, ctx.Err())
	}
}

// drain merges items into a single announce message and calls onDrain.
func (aq *AnnounceQueue) drain(sessionKey string, items []AnnounceQueueItem, meta AnnounceMetadata) {
	if len(items) == 0 || aq.onDrain == nil {
		return
	}

	aq.onDrain(sessionKey, items, meta)
}

// FormatBatchedAnnounce builds the announce content for a batch of items.
// roster provides deterministic task labels+statuses to prevent LLM hallucination.
func FormatBatchedAnnounce(items []AnnounceQueueItem, roster SubagentRoster) string {
	if len(items) == 1 {
		// Single item: use the same format as before (no batching overhead)
		item := items[0]
		statusLabel := "completed successfully"
		if item.Status == "failed" {
			statusLabel = "failed: " + item.Result
		} else if item.Status == "cancelled" {
			statusLabel = "was cancelled"
		}

		replyInstruction := BuildReplyInstruction(roster)

		return fmt.Sprintf(
			"[System Message] A subagent task %q just %s (task=%s, parent=%s, depth=%d).\n\n"+
				"Result:\n%s\n\n"+
				"Stats: runtime %s, iterations %d, tokens %d in / %d out\n\n"+
				"%s",
			item.Label, statusLabel, item.SubagentID, item.ParentTaskID, item.Depth, item.Result,
			item.Runtime.Round(time.Millisecond), item.Iterations,
			item.InputTokens, item.OutputTokens,
			replyInstruction,
		)
	}

	// Multiple items: batched format
	var sb strings.Builder
	sb.WriteString("[System Message] Multiple subagent tasks completed:\n")

	for i, item := range items {
		statusLabel := "completed"
		if item.Status == "failed" {
			statusLabel = "failed"
		} else if item.Status == "cancelled" {
			statusLabel = "cancelled"
		}

		sb.WriteString(fmt.Sprintf(
			"\n---\nTask #%d: %q %s (task=%s, parent=%s, depth=%d, runtime %s, iterations %d, tokens %d/%d)\nResult: %s\n",
			i+1, item.Label, statusLabel, item.SubagentID, item.ParentTaskID, item.Depth,
			item.Runtime.Round(time.Millisecond), item.Iterations,
			item.InputTokens, item.OutputTokens,
			item.Result,
		))
	}

	sb.WriteString("---\n\n")
	sb.WriteString(BuildReplyInstruction(roster))

	return sb.String()
}

// buildReplyInstruction generates the instruction block for the parent LLM,
// including a deterministic roster of all subagent tasks with their statuses.
func BuildReplyInstruction(roster SubagentRoster) string {
	running := roster.Active
	if running == 0 {
		for _, entry := range roster.Entries {
			if entry.Status == TaskStatusRunning {
				running++
			}
		}
	}

	// Build roster block
	var rosterBlock string
	if len(roster.Entries) > 0 {
		var sb strings.Builder
		sb.WriteString(fmt.Sprintf(
			"Subagent roster (%d active / %d max; %d retained total):\n",
			running, roster.MaxPerAgent, roster.Total,
		))
		for _, e := range roster.Entries {
			sb.WriteString(fmt.Sprintf("  [%-9s]  %s\n", e.Status, e.Label))
		}
		rosterBlock = sb.String()
	}

	if running > 0 {
		return fmt.Sprintf(
			"%s\n"+
				"%d subagent(s) still running. "+
				"If they are part of the same workflow, wait for the remaining results "+
				"before sending a user update. If they are unrelated, respond normally "+
				"using only the result above. "+
				"Do NOT copy or echo the [System Message] block verbatim — rewrite in your own voice. "+
				"Reply ONLY: NO_REPLY if this result was already delivered to the user.",
			rosterBlock, running,
		)
	}

	return rosterBlock +
		"\nAll subagent tasks completed. Convert the result above into your normal assistant voice and " +
		"send that user-facing update now. Keep this internal context private " +
		"(don't mention system/log/stats/session details or announce type), " +
		"and do NOT copy the [System Message] block verbatim. " +
		"Reply ONLY: NO_REPLY if this exact result was already delivered to the user."
}