// Package orchestration implements the multi-bot orchestrator runtime.
// The orchestrator intercepts Matrix events in managed rooms and coordinates
// which bot responds via the in-process bus.
package orchestration

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"sync"

	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/id"

	"github.com/enmanuel/agents/internal/config"
	"github.com/enmanuel/agents/pkg/decision"
	coretypes "github.com/enmanuel/agents/pkg/llm"
	"github.com/enmanuel/agents/pkg/orchestration"
	"github.com/enmanuel/agents/shell/bus"
	shelllm "github.com/enmanuel/agents/shell/llm"
)

// RoomScanner is a read-only view of Matrix rooms and members.
// Satisfied by *mautrix.Client.
type RoomScanner interface {
	JoinedRooms(ctx context.Context) (*mautrix.RespJoinedRooms, error)
	JoinedMembers(ctx context.Context, roomID id.RoomID) (*mautrix.RespJoinedMembers, error)
}

// Orchestrator coordinates multi-bot rooms. It has no Matrix identity —
// it intercepts events before they reach bots and delegates via the bus.
type Orchestrator struct {
	cfg          *config.SpecialConfig
	llm          coretypes.CompleteFunc
	bus          *bus.Bus
	logger       *slog.Logger

	// mu protects managedRooms, participants, and knownBotIDs.
	mu           sync.RWMutex
	managedRooms map[string][]string                       // roomID → []botID
	staticRooms  map[string]struct{}                       // rooms from YAML (never auto-removed)
	participants map[string]orchestration.ParticipantInfo   // botID → info
	knownBotIDs  map[string]string                         // matrixUserID → botID

	// Scanner for room/member discovery (set via SetScanner after startup)
	scanner RoomScanner

	// Prompts loaded from files
	routingPrompt    string
	qualityPrompt    string
	refinementPrompt string

	// Dedup: multiple bots in the same room will each trigger Intercept().
	// We use a set of "room:sender:content" keys to ensure only one fires.
	seenMu sync.Mutex
	seen   map[string]bool
}

// New creates an Orchestrator from its config.
func New(cfg *config.SpecialConfig, agentBus *bus.Bus, logger *slog.Logger) (*Orchestrator, error) {
	llmFunc, err := shelllm.FromConfig(cfg.LLM.Primary, logger.With("component", "llm"))
	if err != nil {
		return nil, fmt.Errorf("orchestrator LLM: %w", err)
	}

	managed := make(map[string][]string)
	static := make(map[string]struct{})
	for _, room := range cfg.Orchestration.Rooms {
		if room.RoomID == "" {
			continue // skip empty room IDs (unset env vars)
		}
		managed[room.RoomID] = room.Participants
		static[room.RoomID] = struct{}{}
	}

	o := &Orchestrator{
		cfg:          cfg,
		llm:          llmFunc,
		bus:          agentBus,
		managedRooms: managed,
		staticRooms:  static,
		participants: make(map[string]orchestration.ParticipantInfo),
		knownBotIDs:  make(map[string]string),
		logger:       logger,
		seen:         make(map[string]bool),
	}

	if err := o.loadPrompts(); err != nil {
		return nil, fmt.Errorf("load prompts: %w", err)
	}

	return o, nil
}

// SetScanner injects a Matrix client for room/member discovery.
// Must be called before ScanExistingRooms.
func (o *Orchestrator) SetScanner(s RoomScanner) {
	o.scanner = s
}

// RegisterParticipant adds bot metadata used for LLM routing decisions.
func (o *Orchestrator) RegisterParticipant(info orchestration.ParticipantInfo) {
	o.mu.Lock()
	o.participants[info.ID] = info
	if info.MatrixUserID != "" {
		o.knownBotIDs[info.MatrixUserID] = info.ID
	}
	o.mu.Unlock()
	o.logger.Debug("registered participant", "bot", info.ID, "matrix_uid", info.MatrixUserID)
}

// ScanExistingRooms discovers rooms where ≥2 registered bots are members.
// Called once at startup after all participants are registered.
func (o *Orchestrator) ScanExistingRooms(ctx context.Context) {
	if o.scanner == nil {
		o.logger.Warn("no scanner set, skipping room discovery")
		return
	}

	resp, err := o.scanner.JoinedRooms(ctx)
	if err != nil {
		o.logger.Error("failed to list joined rooms for discovery", "err", err)
		return
	}

	for _, roomID := range resp.JoinedRooms {
		o.evaluateRoom(ctx, roomID.String())
	}

	o.mu.RLock()
	count := len(o.managedRooms)
	o.mu.RUnlock()
	o.logger.Info("room discovery complete", "managed_rooms", count)
}

// evaluateRoom checks if a room has ≥2 registered bots and updates managedRooms.
func (o *Orchestrator) evaluateRoom(ctx context.Context, roomID string) {
	if o.scanner == nil {
		return
	}

	members, err := o.scanner.JoinedMembers(ctx, id.RoomID(roomID))
	if err != nil {
		o.logger.Warn("evaluateRoom: failed to fetch members", "room", roomID, "err", err)
		return
	}

	// Collect which registered bots are in this room
	o.mu.RLock()
	var presentBots []string
	for matrixUID, botID := range o.knownBotIDs {
		if _, ok := members.Joined[id.UserID(matrixUID)]; ok {
			presentBots = append(presentBots, botID)
		}
	}
	_, isStatic := o.staticRooms[roomID]
	o.mu.RUnlock()

	// Static rooms (from YAML) are never auto-managed
	if isStatic {
		return
	}

	o.mu.Lock()
	defer o.mu.Unlock()

	if len(presentBots) >= 2 {
		prev, already := o.managedRooms[roomID]
		if !already {
			o.managedRooms[roomID] = presentBots
			o.logger.Info("auto-managing room", "room", roomID, "bots", presentBots)
		} else if len(prev) != len(presentBots) {
			o.managedRooms[roomID] = presentBots
			o.logger.Info("updated room participants", "room", roomID, "bots", presentBots)
		}
	} else {
		if _, was := o.managedRooms[roomID]; was {
			delete(o.managedRooms, roomID)
			o.logger.Info("stopped managing room", "room", roomID, "remaining_bots", len(presentBots))
		}
	}
}

// NotifyMembership is called by bot listeners when a room membership changes.
// It re-evaluates whether the room should be auto-managed.
func (o *Orchestrator) NotifyMembership(ctx context.Context, roomID, userID, membership string) {
	o.mu.RLock()
	_, isBot := o.knownBotIDs[userID]
	o.mu.RUnlock()
	if !isBot {
		return // only care about bot membership changes
	}

	o.logger.Debug("bot membership change, re-evaluating room",
		"room", roomID, "user", userID, "membership", membership)
	go o.evaluateRoom(ctx, roomID)
}

// ShouldIntercept returns true if the room is managed by this orchestrator.
func (o *Orchestrator) ShouldIntercept(roomID string) bool {
	o.mu.RLock()
	_, ok := o.managedRooms[roomID]
	o.mu.RUnlock()
	return ok
}

// Intercept is the InterceptFunc used by bot listeners. It checks if the
// room is managed and, if so, starts the orchestration pipeline asynchronously.
// Returns true if the event was intercepted (all bots in the room should return true,
// but only the first one triggers actual routing — the rest are deduped).
func (o *Orchestrator) Intercept(ctx context.Context, msgCtx decision.MessageContext) bool {
	if !o.ShouldIntercept(msgCtx.RoomID) {
		return false
	}

	// Ignore messages from known bots to prevent feedback loops.
	o.mu.RLock()
	_, senderIsBot := o.knownBotIDs[msgCtx.SenderID]
	o.mu.RUnlock()
	if senderIsBot {
		return true // suppress but don't route — bot's own message
	}

	// Dedup: multiple bots receive the same event. Only route once.
	key := msgCtx.RoomID + ":" + msgCtx.SenderID + ":" + msgCtx.Content
	o.seenMu.Lock()
	if o.seen[key] {
		o.seenMu.Unlock()
		return true // still intercept (don't let the bot handle it) but don't route again
	}
	o.seen[key] = true
	o.seenMu.Unlock()

	// Route asynchronously so the listener isn't blocked.
	// Clean up the dedup key after routing completes.
	go func() {
		defer func() {
			o.seenMu.Lock()
			delete(o.seen, key)
			o.seenMu.Unlock()
		}()
		if err := o.Route(ctx, msgCtx); err != nil {
			o.logger.Error("orchestration failed", "room", msgCtx.RoomID, "err", err)
		}
	}()
	return true
}

// Route is the main entry point. Called when a human posts in a managed room.
// It decides which bot(s) should respond and dispatches tasks via the bus.
func (o *Orchestrator) Route(ctx context.Context, msgCtx decision.MessageContext) error {
	o.mu.RLock()
	participants, ok := o.managedRooms[msgCtx.RoomID]
	participantsCopy := append([]string(nil), participants...)
	o.mu.RUnlock()

	if !ok {
		return fmt.Errorf("room %s is not managed", msgCtx.RoomID)
	}

	o.logger.Info("orchestrating message",
		"room", msgCtx.RoomID,
		"sender", msgCtx.SenderID,
		"participants", participantsCopy,
		"content_preview", truncate(msgCtx.Content, 80),
	)

	// Optimization: single bot → dispatch directly without LLM
	if len(participantsCopy) == 1 {
		o.logger.Debug("single participant, dispatching directly", "bot", participantsCopy[0])
		_, err := o.dispatchAndWait(ctx, participantsCopy[0], msgCtx, 0, nil)
		return err
	}

	var responses []orchestration.BotResponse
	var lastBot string
	maxIter := o.cfg.Orchestration.MaxIterations
	if maxIter <= 0 {
		maxIter = 3
	}

	for i := 0; i < maxIter; i++ {
		// Route: decide which bot responds
		var target string
		var err error

		if i == 0 {
			rd, routeErr := o.routeInitial(ctx, msgCtx.Content, participantsCopy)
			if routeErr != nil {
				o.logger.Error("routing failed, falling back to first participant", "err", routeErr)
				target = participantsCopy[0]
			} else {
				target = rd.TargetBotID
				o.logger.Info("routed to bot",
					"bot", target,
					"confidence", rd.Confidence,
					"reason", rd.Reason,
					"iteration", i,
				)
			}
		} else {
			rd, routeErr := o.routeRefinement(ctx, msgCtx.Content, responses, participantsCopy, lastBot)
			if routeErr != nil {
				o.logger.Warn("refinement routing failed, stopping pipeline", "err", routeErr)
				break
			}
			target = rd.TargetBotID
			o.logger.Info("refinement routed to bot",
				"bot", target,
				"reason", rd.Reason,
				"iteration", i,
			)
		}

		// Dispatch: send TaskEvent to bot via bus and wait for response
		response, err := o.dispatchAndWait(ctx, target, msgCtx, i, responses)
		if err != nil {
			o.logger.Error("dispatch failed", "bot", target, "err", err)
			break
		}

		responses = append(responses, response)
		lastBot = target

		o.logger.Info("bot responded",
			"bot", target,
			"response_len", len(response.Text),
			"iteration", i,
		)

		// Fallback: detect circular conversations before quality evaluation
		if o.detectRepetition(responses) {
			o.logger.Warn("repetition detected, stopping pipeline to prevent circular conversation",
				"iteration", i+1,
				"total_responses", len(responses),
			)
			break
		}

		// Evaluate quality (Fase 3)
		score := o.evaluate(ctx, msgCtx.Content, response)
		o.logger.Info("quality evaluated",
			"score", score.Score,
			"continue", score.Continue,
			"reason", score.Reason,
			"iteration", i,
		)

		if score.Score >= o.cfg.Orchestration.QualityThreshold || !score.Continue {
			o.logger.Info("pipeline complete",
				"iterations", i+1,
				"final_score", score.Score,
			)
			break
		}
	}

	return nil
}

// dispatchAndWait sends a TaskEvent to a bot and waits for its response.
func (o *Orchestrator) dispatchAndWait(
	ctx context.Context,
	botID string,
	msgCtx decision.MessageContext,
	iteration int,
	previousResponses []orchestration.BotResponse,
) (orchestration.BotResponse, error) {
	taskID := fmt.Sprintf("orch-%s-%s-%d", msgCtx.RoomID, botID, iteration)

	task := orchestration.TaskEvent{
		TaskID:            taskID,
		TargetBotID:       botID,
		TargetRoomID:      msgCtx.RoomID,
		OriginalSender:    msgCtx.SenderID,
		OriginalQuestion:  msgCtx.Content,
		Iteration:         iteration,
		PreviousResponses: previousResponses,
	}

	taskJSON, err := orchestration.MarshalTaskEvent(task)
	if err != nil {
		return orchestration.BotResponse{}, fmt.Errorf("marshal task: %w", err)
	}

	msg := bus.AgentMessage{
		From:    bus.AgentID(o.cfg.Special.ID),
		To:      bus.AgentID(botID),
		Kind:    bus.KindTask,
		Payload: map[string]string{"task_json": taskJSON},
	}

	timeout := o.cfg.Orchestration.DelegationTimeout
	if timeout <= 0 {
		timeout = 30_000_000_000 // 30s default
	}

	reply, err := o.bus.SendAndWait(ctx, msg, taskID, timeout)
	if err != nil {
		return orchestration.BotResponse{}, err
	}

	resultJSON, ok := reply.Payload["result_json"]
	if !ok {
		return orchestration.BotResponse{}, fmt.Errorf("reply missing result_json")
	}

	result, err := orchestration.UnmarshalTaskResult(resultJSON)
	if err != nil {
		return orchestration.BotResponse{}, fmt.Errorf("unmarshal result: %w", err)
	}

	if result.Error != "" {
		return orchestration.BotResponse{}, fmt.Errorf("bot %s error: %s", botID, result.Error)
	}

	return orchestration.BotResponse{
		BotID: botID,
		Text:  result.Text,
	}, nil
}

// loadPrompts reads the orchestrator's prompt files.
func (o *Orchestrator) loadPrompts() error {
	base := filepath.Join("agents", "specials", "orchestrator", "prompts")

	routing, err := os.ReadFile(filepath.Join(base, "routing.md"))
	if err != nil {
		return fmt.Errorf("routing prompt: %w", err)
	}
	o.routingPrompt = string(routing)

	quality, err := os.ReadFile(filepath.Join(base, "quality.md"))
	if err != nil {
		return fmt.Errorf("quality prompt: %w", err)
	}
	o.qualityPrompt = string(quality)

	refinement, err := os.ReadFile(filepath.Join(base, "refinement.md"))
	if err != nil {
		return fmt.Errorf("refinement prompt: %w", err)
	}
	o.refinementPrompt = string(refinement)

	return nil
}

// buildParticipantsList formats participant info for LLM prompts.
func (o *Orchestrator) buildParticipantsList(botIDs []string, exclude string) string {
	o.mu.RLock()
	defer o.mu.RUnlock()
	var sb strings.Builder
	for _, id := range botIDs {
		if id == exclude {
			continue
		}
		info, ok := o.participants[id]
		if !ok {
			sb.WriteString(fmt.Sprintf("- %s: (no description available)\n", id))
			continue
		}
		caps := ""
		if len(info.Capabilities) > 0 {
			caps = fmt.Sprintf(" (capabilities: %s)", strings.Join(info.Capabilities, ", "))
		}
		sb.WriteString(fmt.Sprintf("- %s: %s%s\n", info.ID, info.Description, caps))
	}
	return sb.String()
}

// detectRepetition checks if a new response is too similar to previous responses,
// indicating a circular conversation that should be stopped.
// Returns true if the conversation should be terminated.
func (o *Orchestrator) detectRepetition(responses []orchestration.BotResponse) bool {
	if len(responses) < 2 {
		return false
	}

	threshold := o.cfg.Orchestration.RepetitionThreshold
	if threshold <= 0 {
		threshold = 0.6 // default
	}

	latest := responses[len(responses)-1].Text
	for i := 0; i < len(responses)-1; i++ {
		if similarity(latest, responses[i].Text) >= threshold {
			return true
		}
	}
	return false
}

// similarity computes a simple bigram-based similarity ratio between two strings.
// Returns a value between 0.0 (completely different) and 1.0 (identical).
func similarity(a, b string) float64 {
	if a == b {
		return 1.0
	}
	a = strings.ToLower(strings.TrimSpace(a))
	b = strings.ToLower(strings.TrimSpace(b))
	if a == b {
		return 1.0
	}
	if len(a) < 2 || len(b) < 2 {
		return 0.0
	}

	bigramsA := makeBigrams(a)
	bigramsB := makeBigrams(b)

	// Count intersection
	intersection := 0
	for bg, countA := range bigramsA {
		if countB, ok := bigramsB[bg]; ok {
			if countA < countB {
				intersection += countA
			} else {
				intersection += countB
			}
		}
	}

	totalA := 0
	for _, c := range bigramsA {
		totalA += c
	}
	totalB := 0
	for _, c := range bigramsB {
		totalB += c
	}

	if totalA+totalB == 0 {
		return 0.0
	}
	return float64(2*intersection) / float64(totalA+totalB)
}

func makeBigrams(s string) map[string]int {
	runes := []rune(s)
	bgs := make(map[string]int, len(runes))
	for i := 0; i < len(runes)-1; i++ {
		bg := string(runes[i : i+2])
		bgs[bg]++
	}
	return bgs
}

func truncate(s string, n int) string {
	runes := []rune(s)
	if len(runes) <= n {
		return s
	}
	return string(runes[:n]) + "..."
}