package agent

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"strings"

	sdk "github.com/memohai/twilight-ai/sdk"

	"github.com/memohai/memoh/internal/agent/tools"
	"github.com/memohai/memoh/internal/models"
	"github.com/memohai/memoh/internal/workspace/bridge"
)

// Agent is the core agent that handles LLM interactions.
type Agent struct {
	client         *sdk.Client
	toolProviders  []tools.ToolProvider
	bridgeProvider bridge.Provider
	logger         *slog.Logger
}

// New creates a new Agent with the given dependencies.
func New(deps Deps) *Agent {
	logger := deps.Logger
	if logger == nil {
		logger = slog.Default()
	}
	return &Agent{
		client:         sdk.NewClient(),
		bridgeProvider: deps.BridgeProvider,
		logger:         logger.With(slog.String("service", "agent")),
	}
}

// BridgeProvider returns the underlying bridge provider (workspace manager).
func (a *Agent) BridgeProvider() bridge.Provider {
	return a.bridgeProvider
}

// SetToolProviders sets the tool providers after construction.
// This allows breaking dependency cycles in the DI graph.
func (a *Agent) SetToolProviders(providers []tools.ToolProvider) {
	a.toolProviders = providers
}

// Stream runs the agent in streaming mode, emitting events to the returned channel.
func (a *Agent) Stream(ctx context.Context, cfg RunConfig) <-chan StreamEvent {
	ch := make(chan StreamEvent)
	go func() {
		defer close(ch)
		a.runStream(ctx, cfg, ch)
	}()
	return ch
}

// Generate runs the agent in non-streaming mode, returning the complete result.
func (a *Agent) Generate(ctx context.Context, cfg RunConfig) (*GenerateResult, error) {
	return a.runGenerate(ctx, cfg)
}

func (a *Agent) runStream(ctx context.Context, cfg RunConfig, ch chan<- StreamEvent) {
	// Stream emitter: tools targeting the current conversation push
	// side-effect events (attachments, reactions, speech) directly here.
	streamEmitter := tools.StreamEmitter(func(evt tools.ToolStreamEvent) {
		ch <- toolStreamEventToAgentEvent(evt)
	})

	var sdkTools []sdk.Tool
	if cfg.SupportsToolCall {
		var err error
		sdkTools, err = a.assembleTools(ctx, cfg, streamEmitter)
		if err != nil {
			ch <- StreamEvent{Type: EventError, Error: fmt.Sprintf("assemble tools: %v", err)}
			return
		}
	}
	sdkTools, readMediaState := decorateReadMediaTools(cfg.Model, sdkTools)

	// Loop detection setup
	var textLoopGuard *TextLoopGuard
	var textLoopProbeBuffer *TextLoopProbeBuffer
	var toolLoopGuard *ToolLoopGuard
	toolLoopAbortCallIDs := make(map[string]struct{})
	if cfg.LoopDetection.Enabled {
		textLoopGuard = NewTextLoopGuard(LoopDetectedStreakThreshold, LoopDetectedMinNewGramsPerChunk, SentialOptions{})
		textLoopProbeBuffer = NewTextLoopProbeBuffer(LoopDetectedProbeChars, func(text string) {
			result := textLoopGuard.Inspect(text)
			if result.Abort {
				a.logger.Warn("text loop detected, will abort")
			}
		})
		toolLoopGuard = NewToolLoopGuard(ToolLoopRepeatThreshold, ToolLoopWarningsBeforeAbort)
	}

	// Wrap tools with loop detection
	if toolLoopGuard != nil {
		sdkTools = wrapToolsWithLoopGuard(sdkTools, toolLoopGuard, toolLoopAbortCallIDs)
	}

	var prepareStep func(*sdk.GenerateParams) *sdk.GenerateParams
	if readMediaState != nil {
		prepareStep = readMediaState.prepareStep
	}

	initialMsgCount := len(cfg.Messages)

	if cfg.InjectCh != nil {
		basePrepare := prepareStep
		prepareStep = func(p *sdk.GenerateParams) *sdk.GenerateParams {
			if basePrepare != nil {
				if override := basePrepare(p); override != nil {
					p = override
				}
			}
			for {
				select {
				case injected, ok := <-cfg.InjectCh:
					if !ok {
						break
					}
					text := strings.TrimSpace(injected.HeaderifiedText)
					if text == "" {
						text = strings.TrimSpace(injected.Text)
					}
					if text != "" || (cfg.SupportsImageInput && len(injected.ImageParts) > 0) {
						insertAfter := len(p.Messages) - initialMsgCount
						var extra []sdk.MessagePart
						if cfg.SupportsImageInput {
							for _, img := range injected.ImageParts {
								if strings.TrimSpace(img.Image) != "" {
									extra = append(extra, img)
								}
							}
						}
						p.Messages = append(p.Messages, sdk.UserMessage(text, extra...))
						if cfg.InjectedRecorder != nil {
							cfg.InjectedRecorder(text, insertAfter)
						}
						a.logger.Info("injected user message into agent stream",
							slog.String("bot_id", cfg.Identity.BotID),
							slog.Int("insert_after", insertAfter),
							slog.Int("image_parts", len(extra)),
						)
					}
					continue
				default:
				}
				break
			}
			return p
		}
	}

	opts := a.buildGenerateOptions(cfg, sdkTools, prepareStep)

	streamResult, err := a.client.StreamText(ctx, opts...)
	if err != nil {
		ch <- StreamEvent{Type: EventError, Error: fmt.Sprintf("stream start: %v", err)}
		return
	}

	ch <- StreamEvent{Type: EventAgentStart}

	var allText strings.Builder
	aborted := false

	for part := range streamResult.Stream {
		if ctx.Err() != nil {
			aborted = true
			break
		}

		switch p := part.(type) {
		case *sdk.StartPart:
			_ = p // stream start already emitted

		case *sdk.TextStartPart:
			ch <- StreamEvent{Type: EventTextStart}

		case *sdk.TextDeltaPart:
			if p.Text != "" {
				if textLoopProbeBuffer != nil {
					textLoopProbeBuffer.Push(p.Text)
				}
				ch <- StreamEvent{Type: EventTextDelta, Delta: p.Text}
				allText.WriteString(p.Text)
			}

		case *sdk.TextEndPart:
			if textLoopProbeBuffer != nil {
				textLoopProbeBuffer.Flush()
			}
			ch <- StreamEvent{Type: EventTextEnd}

		case *sdk.ReasoningStartPart:
			ch <- StreamEvent{Type: EventReasoningStart}

		case *sdk.ReasoningDeltaPart:
			ch <- StreamEvent{Type: EventReasoningDelta, Delta: p.Text}

		case *sdk.ReasoningEndPart:
			ch <- StreamEvent{Type: EventReasoningEnd}

		case *sdk.StreamToolCallPart:
			if textLoopProbeBuffer != nil {
				textLoopProbeBuffer.Flush()
			}
			ch <- StreamEvent{
				Type:       EventToolCallStart,
				ToolName:   p.ToolName,
				ToolCallID: p.ToolCallID,
				Input:      p.Input,
			}

		case *sdk.ToolProgressPart:
			ch <- StreamEvent{
				Type:       EventToolCallProgress,
				ToolName:   p.ToolName,
				ToolCallID: p.ToolCallID,
				Progress:   p.Content,
			}

		case *sdk.StreamToolResultPart:
			shouldAbort := false
			if _, ok := toolLoopAbortCallIDs[p.ToolCallID]; ok {
				delete(toolLoopAbortCallIDs, p.ToolCallID)
				shouldAbort = true
			}
			ch <- StreamEvent{
				Type:       EventToolCallEnd,
				ToolName:   p.ToolName,
				ToolCallID: p.ToolCallID,
				Input:      p.Input,
				Result:     p.Output,
			}
			if shouldAbort {
				a.logger.Warn("tool loop abort triggered", slog.String("tool_call_id", p.ToolCallID))
				aborted = true
			}

		case *sdk.StreamToolErrorPart:
			ch <- StreamEvent{
				Type:       EventToolCallEnd,
				ToolName:   p.ToolName,
				ToolCallID: p.ToolCallID,
				Error:      p.Error.Error(),
			}

		case *sdk.StreamFilePart:
			mediaType := p.File.MediaType
			if mediaType == "" {
				mediaType = "image/png"
			}
			ch <- StreamEvent{
				Type: EventAttachment,
				Attachments: []FileAttachment{{
					Type: "image",
					URL:  fmt.Sprintf("data:%s;base64,%s", mediaType, p.File.Data),
					Mime: mediaType,
				}},
			}

		case *sdk.ErrorPart:
			ch <- StreamEvent{Type: EventError, Error: p.Error.Error()}
			aborted = true

		case *sdk.AbortPart:
			aborted = true

		case *sdk.FinishPart:
			// handled after loop
		}

		if aborted {
			break
		}
	}

	if textLoopProbeBuffer != nil {
		textLoopProbeBuffer.Flush()
	}

	finalMessages := streamResult.Messages
	if readMediaState != nil {
		finalMessages = readMediaState.mergeMessages(streamResult.Steps, finalMessages)
	}
	var totalUsage sdk.Usage
	for _, step := range streamResult.Steps {
		totalUsage.InputTokens += step.Usage.InputTokens
		totalUsage.OutputTokens += step.Usage.OutputTokens
		totalUsage.TotalTokens += step.Usage.TotalTokens
		totalUsage.ReasoningTokens += step.Usage.ReasoningTokens
		totalUsage.CachedInputTokens += step.Usage.CachedInputTokens
		totalUsage.InputTokenDetails.NoCacheTokens += step.Usage.InputTokenDetails.NoCacheTokens
		totalUsage.InputTokenDetails.CacheReadTokens += step.Usage.InputTokenDetails.CacheReadTokens
		totalUsage.InputTokenDetails.CacheWriteTokens += step.Usage.InputTokenDetails.CacheWriteTokens
		totalUsage.OutputTokenDetails.TextTokens += step.Usage.OutputTokenDetails.TextTokens
		totalUsage.OutputTokenDetails.ReasoningTokens += step.Usage.OutputTokenDetails.ReasoningTokens
	}
	usageJSON, _ := json.Marshal(totalUsage)

	termEvent := StreamEvent{
		Messages: mustMarshal(finalMessages),
		Usage:    usageJSON,
	}
	if aborted {
		termEvent.Type = EventAgentAbort
	} else {
		termEvent.Type = EventAgentEnd
	}
	ch <- termEvent
}

func (a *Agent) runGenerate(ctx context.Context, cfg RunConfig) (*GenerateResult, error) {
	// Collecting emitter: tools push side-effect events here during generation.
	var collected []tools.ToolStreamEvent
	collectEmitter := tools.StreamEmitter(func(evt tools.ToolStreamEvent) {
		collected = append(collected, evt)
	})

	var sdkTools []sdk.Tool
	if cfg.SupportsToolCall {
		var err error
		sdkTools, err = a.assembleTools(ctx, cfg, collectEmitter)
		if err != nil {
			return nil, fmt.Errorf("assemble tools: %w", err)
		}
	}
	sdkTools, readMediaState := decorateReadMediaTools(cfg.Model, sdkTools)

	var toolLoopGuard *ToolLoopGuard
	var textLoopGuard *TextLoopGuard
	toolLoopAbortCallIDs := make(map[string]struct{})
	if cfg.LoopDetection.Enabled {
		toolLoopGuard = NewToolLoopGuard(ToolLoopRepeatThreshold, ToolLoopWarningsBeforeAbort)
		textLoopGuard = NewTextLoopGuard(LoopDetectedStreakThreshold, LoopDetectedMinNewGramsPerChunk, SentialOptions{})
	}

	if toolLoopGuard != nil {
		sdkTools = wrapToolsWithLoopGuard(sdkTools, toolLoopGuard, toolLoopAbortCallIDs)
	}

	var prepareStep func(*sdk.GenerateParams) *sdk.GenerateParams
	if readMediaState != nil {
		prepareStep = readMediaState.prepareStep
	}
	opts := a.buildGenerateOptions(cfg, sdkTools, prepareStep)
	opts = append(opts,
		sdk.WithOnStep(func(step *sdk.StepResult) *sdk.GenerateParams {
			if cfg.LoopDetection.Enabled {
				if len(toolLoopAbortCallIDs) > 0 {
					return nil // stop
				}
				if textLoopGuard != nil && isNonEmptyString(step.Text) {
					result := textLoopGuard.Inspect(step.Text)
					if result.Abort {
						return nil // stop
					}
				}
			}
			return nil
		}),
	)

	genResult, err := a.client.GenerateTextResult(ctx, opts...)
	if err != nil {
		return nil, fmt.Errorf("generate: %w", err)
	}

	// Drain collected tool-emitted side effects into the result.
	var attachments []FileAttachment
	var reactions []ReactionItem
	var speeches []SpeechItem
	for _, evt := range collected {
		switch evt.Type {
		case tools.StreamEventAttachment:
			for _, a := range evt.Attachments {
				attachments = append(attachments, FileAttachment{
					Type: a.Type, Path: a.Path, URL: a.URL,
					Mime: a.Mime, Name: a.Name,
					ContentHash: a.ContentHash, Size: a.Size,
					Metadata: a.Metadata,
				})
			}
		case tools.StreamEventReaction:
			for _, r := range evt.Reactions {
				reactions = append(reactions, ReactionItem{Emoji: r.Emoji})
			}
		case tools.StreamEventSpeech:
			for _, s := range evt.Speeches {
				speeches = append(speeches, SpeechItem{Text: s.Text})
			}
		}
	}

	finalMessages := genResult.Messages
	if readMediaState != nil {
		finalMessages = readMediaState.mergeMessages(genResult.Steps, finalMessages)
	}
	return &GenerateResult{
		Messages:    finalMessages,
		Text:        genResult.Text,
		Attachments: attachments,
		Reactions:   reactions,
		Speeches:    speeches,
		Usage:       &genResult.Usage,
	}, nil
}

func (*Agent) buildGenerateOptions(cfg RunConfig, tools []sdk.Tool, prepareStep func(*sdk.GenerateParams) *sdk.GenerateParams) []sdk.GenerateOption {
	opts := []sdk.GenerateOption{
		sdk.WithModel(cfg.Model),
		sdk.WithMessages(cfg.Messages),
		sdk.WithSystem(cfg.System),
		sdk.WithMaxSteps(-1),
	}
	if len(tools) > 0 && cfg.SupportsToolCall {
		opts = append(opts, sdk.WithTools(tools))
	}
	if prepareStep != nil {
		opts = append(opts, sdk.WithPrepareStep(prepareStep))
	}
	opts = append(opts, models.BuildReasoningOptions(models.SDKModelConfig{
		ClientType: models.ResolveClientType(cfg.Model),
		ReasoningConfig: &models.ReasoningConfig{
			Enabled: cfg.ReasoningEffort != "",
			Effort:  cfg.ReasoningEffort,
		},
	})...)
	return opts
}

// assembleTools collects tools from all registered ToolProviders.
// emitter is injected into the session context so that tools targeting the
// current conversation can push side-effect events (attachments, reactions,
// speech) directly into the agent stream.
func (a *Agent) assembleTools(ctx context.Context, cfg RunConfig, emitter tools.StreamEmitter) ([]sdk.Tool, error) {
	if len(a.toolProviders) == 0 {
		return nil, nil
	}
	skillsMap := make(map[string]tools.SkillDetail, len(cfg.Skills))
	for _, s := range cfg.Skills {
		skillsMap[s.Name] = tools.SkillDetail{
			Description: s.Description,
			Content:     s.Content,
		}
	}
	session := tools.SessionContext{
		BotID:              cfg.Identity.BotID,
		ChatID:             cfg.Identity.ChatID,
		SessionID:          cfg.Identity.SessionID,
		SessionType:        cfg.SessionType,
		ChannelIdentityID:  cfg.Identity.ChannelIdentityID,
		SessionToken:       cfg.Identity.SessionToken,
		CurrentPlatform:    cfg.Identity.CurrentPlatform,
		ReplyTarget:        cfg.Identity.ReplyTarget,
		SupportsImageInput: cfg.SupportsImageInput,
		IsSubagent:         cfg.Identity.IsSubagent,
		Skills:             skillsMap,
		TimezoneLocation:   cfg.Identity.TimezoneLocation,
		Emitter:            emitter,
	}

	var allTools []sdk.Tool
	for _, provider := range a.toolProviders {
		providerTools, err := provider.Tools(ctx, session)
		if err != nil {
			a.logger.Warn("tool provider failed", slog.Any("error", err))
			continue
		}
		allTools = append(allTools, providerTools...)
	}
	return allTools, nil
}

// toolStreamEventToAgentEvent converts a tool-layer ToolStreamEvent into an
// agent-layer StreamEvent suitable for the output channel.
func toolStreamEventToAgentEvent(evt tools.ToolStreamEvent) StreamEvent {
	switch evt.Type {
	case tools.StreamEventAttachment:
		atts := make([]FileAttachment, 0, len(evt.Attachments))
		for _, a := range evt.Attachments {
			atts = append(atts, FileAttachment{
				Type: a.Type, Path: a.Path, URL: a.URL,
				Mime: a.Mime, Name: a.Name,
				ContentHash: a.ContentHash, Size: a.Size,
				Metadata: a.Metadata,
			})
		}
		return StreamEvent{Type: EventAttachment, Attachments: atts}
	case tools.StreamEventReaction:
		rs := make([]ReactionItem, 0, len(evt.Reactions))
		for _, r := range evt.Reactions {
			rs = append(rs, ReactionItem{Emoji: r.Emoji})
		}
		return StreamEvent{Type: EventReaction, Reactions: rs}
	case tools.StreamEventSpeech:
		ss := make([]SpeechItem, 0, len(evt.Speeches))
		for _, s := range evt.Speeches {
			ss = append(ss, SpeechItem{Text: s.Text})
		}
		return StreamEvent{Type: EventSpeech, Speeches: ss}
	default:
		return StreamEvent{}
	}
}

func wrapToolsWithLoopGuard(tools []sdk.Tool, guard *ToolLoopGuard, abortCallIDs map[string]struct{}) []sdk.Tool {
	wrapped := make([]sdk.Tool, len(tools))
	for i, tool := range tools {
		originalExecute := tool.Execute
		toolName := tool.Name
		wrapped[i] = tool
		wrapped[i].Execute = func(ctx *sdk.ToolExecContext, input any) (any, error) {
			warn, abort := guard.Guard(toolName, input)
			if abort {
				abortCallIDs[ctx.ToolCallID] = struct{}{}
				return map[string]any{
					"isError": true,
					"content": []map[string]any{{
						"type": "text",
						"text": ToolLoopDetectedAbortMessage,
					}},
				}, errors.New(ToolLoopDetectedAbortMessage)
			}
			if warn {
				return map[string]any{
					ToolLoopWarningKey: true,
					"content": []map[string]any{{
						"type": "text",
						"text": ToolLoopWarningText,
					}},
				}, nil
			}
			return originalExecute(ctx, input)
		}
	}
	return wrapped
}