package windsurf

import (
	"context"
	"fmt"
	"strings"
	"time"
)

const (
	RawGetChatMessageRPC = "/exa.language_server_pb.LanguageServerService/RawGetChatMessage"

	SourceUser      = 1
	SourceSystem    = 2
	SourceAssistant = 3
	SourceTool      = 4
)

type ChatMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
	// Images 当前消息携带的图片（通常只有 user role 才非空）。
	// 仅用于发送/replay。CascadeImage.Base64Data 不应出现在持久化/日志/指纹中。
	Images []CascadeImage `json:"images,omitempty"`
	// ImageDigests 仅摘要视图（含 sha256 / mime / byte_len / caption，不含 base64）。
	// 供 conversation pool 指纹与日志使用。
	ImageDigests []ImageDigest `json:"image_digests,omitempty"`
}

type LegacyChatDelta struct {
	Text       string
	InProgress bool
	IsError    bool
}

func encodeTimestamp() []byte {
	now := time.Now()
	secs := uint64(now.Unix())
	nanos := uint64(now.Nanosecond())
	out := encodeVarintField(1, secs)
	if nanos > 0 {
		out = append(out, encodeVarintField(2, nanos)...)
	}
	return out
}

func buildChatMessage(content string, source int, conversationID string) []byte {
	var parts []byte
	parts = append(parts, encodeStringField(1, generateUUID())...)
	parts = append(parts, encodeVarintField(2, uint64(source))...)
	parts = append(parts, encodeBytesField(3, encodeTimestamp())...)
	parts = append(parts, encodeStringField(4, conversationID)...)

	if source == SourceAssistant {
		actionGeneric := encodeStringField(1, content)
		action := encodeBytesField(1, actionGeneric)
		parts = append(parts, encodeBytesField(6, action)...)
	} else {
		intentGeneric := encodeStringField(1, content)
		intent := encodeBytesField(1, intentGeneric)
		parts = append(parts, encodeBytesField(5, intent)...)
	}

	return parts
}

func BuildRawGetChatMessageRequest(apiKey string, messages []ChatMessage, modelEnum int, modelName string) []byte {
	var parts []byte
	conversationID := generateUUID()

	parts = append(parts, encodeBytesField(1, buildMetadata(apiKey, generateUUID()))...)

	var systemPrompt string
	for _, msg := range messages {
		if msg.Role == "system" {
			if systemPrompt != "" {
				systemPrompt += "\n"
			}
			systemPrompt += msg.Content
			continue
		}

		var source int
		var text string

		switch msg.Role {
		case "user":
			source = SourceUser
			text = msg.Content
		case "assistant":
			source = SourceAssistant
			text = msg.Content
		case "tool":
			source = SourceUser
			text = "[tool result]: " + msg.Content
		default:
			source = SourceUser
			text = msg.Content
		}

		parts = append(parts, encodeBytesField(2, buildChatMessage(text, source, conversationID))...)
	}

	if systemPrompt != "" {
		parts = append(parts, encodeStringField(3, systemPrompt)...)
	}

	parts = append(parts, encodeVarintField(4, uint64(modelEnum))...)

	if modelName != "" {
		parts = append(parts, encodeStringField(5, modelName)...)
	}

	return parts
}

func ParseRawChatResponse(data []byte) LegacyChatDelta {
	pos := 0
	var deltaMsg []byte
	for pos < len(data) {
		tag, np, ok := ReadVarint(data, pos)
		if !ok {
			break
		}
		pos = np
		fieldNum := tag >> 3
		wireType := tag & 7

		switch wireType {
		case 2:
			length, np2, ok := ReadVarint(data, pos)
			if !ok {
				return LegacyChatDelta{}
			}
			pos = np2
			if pos+int(length) > len(data) {
				return LegacyChatDelta{}
			}
			field := data[pos : pos+int(length)]
			pos += int(length)
			if fieldNum == 1 {
				deltaMsg = field
			}
		case 0:
			_, np2, ok := ReadVarint(data, pos)
			if !ok {
				return LegacyChatDelta{}
			}
			pos = np2
		case 1:
			pos += 8
		case 5:
			pos += 4
		default:
			return LegacyChatDelta{}
		}
	}

	if deltaMsg == nil {
		return LegacyChatDelta{}
	}

	var result LegacyChatDelta
	pos = 0
	for pos < len(deltaMsg) {
		tag, np, ok := ReadVarint(deltaMsg, pos)
		if !ok {
			break
		}
		pos = np
		fieldNum := tag >> 3
		wireType := tag & 7

		switch wireType {
		case 2:
			length, np2, ok := ReadVarint(deltaMsg, pos)
			if !ok {
				return result
			}
			pos = np2
			if pos+int(length) > len(deltaMsg) {
				return result
			}
			field := deltaMsg[pos : pos+int(length)]
			pos += int(length)
			if fieldNum == 5 {
				result.Text = string(field)
			}
		case 0:
			val, np2, ok := ReadVarint(deltaMsg, pos)
			if !ok {
				return result
			}
			pos = np2
			if fieldNum == 6 {
				result.InProgress = val != 0
			} else if fieldNum == 7 {
				result.IsError = val != 0
			}
		case 1:
			pos += 8
		case 5:
			pos += 4
		default:
			pos = len(deltaMsg)
		}
	}

	return result
}

func (l *LocalLSClient) StreamLegacyChat(ctx context.Context, token string, messages []ChatMessage, modelEnum int, modelName string) (string, error) {
	reqBody := BuildRawGetChatMessageRequest(token, messages, modelEnum, modelName)

	respData, err := l.grpcUnaryRaw(ctx, RawGetChatMessageRPC, reqBody)
	if err != nil {
		if strings.Contains(err.Error(), "panel state not found") || strings.Contains(err.Error(), "not_found") {
			_ = l.ForceWarmupCascade(ctx, token)
			respData, err = l.grpcUnaryRaw(ctx, RawGetChatMessageRPC, reqBody)
			if err != nil {
				return "", fmt.Errorf("legacy chat retry: %w", err)
			}
		} else {
			return "", fmt.Errorf("legacy chat: %w", err)
		}
	}

	delta := ParseRawChatResponse(respData)
	if delta.IsError {
		return "", fmt.Errorf("legacy chat error: %s", delta.Text)
	}

	return SanitizePath(delta.Text), nil
}