// Package claude provides request translation functionality for Claude Code API compatibility.
// This package handles the conversion of Claude Code API requests into Gemini CLI-compatible
// JSON format, transforming message contents, system instructions, and tool declarations
// into the format expected by Gemini CLI API clients. It performs JSON data transformation
// to ensure compatibility between Claude Code API format and Gemini CLI API's expected format.
package claude

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"strings"

	"github.com/router-for-me/CLIProxyAPI/v6/internal/cache"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/translator/gemini/common"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
	log "github.com/sirupsen/logrus"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
)

// deriveSessionID generates a stable session ID from the request.
// Uses the hash of the first user message to identify the conversation.
func deriveSessionID(rawJSON []byte) string {
	messages := gjson.GetBytes(rawJSON, "messages")
	if !messages.IsArray() {
		return ""
	}
	for _, msg := range messages.Array() {
		if msg.Get("role").String() == "user" {
			content := msg.Get("content").String()
			if content == "" {
				// Try to get text from content array
				content = msg.Get("content.0.text").String()
			}
			if content != "" {
				h := sha256.Sum256([]byte(content))
				return hex.EncodeToString(h[:16])
			}
		}
	}
	return ""
}

// ConvertClaudeRequestToAntigravity parses and transforms a Claude Code API request into Gemini CLI API format.
// It extracts the model name, system instruction, message contents, and tool declarations
// from the raw JSON request and returns them in the format expected by the Gemini CLI API.
// The function performs the following transformations:
// 1. Extracts the model information from the request
// 2. Restructures the JSON to match Gemini CLI API format
// 3. Converts system instructions to the expected format
// 4. Maps message contents with proper role transformations
// 5. Handles tool declarations and tool choices
// 6. Maps generation configuration parameters
//
// Parameters:
//   - modelName: The name of the model to use for the request
//   - rawJSON: The raw JSON request data from the Claude Code API
//   - stream: A boolean indicating if the request is for a streaming response (unused in current implementation)
//
// Returns:
//   - []byte: The transformed request data in Gemini CLI API format
func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _ bool) []byte {
	rawJSON := bytes.Clone(inputRawJSON)

	// Derive session ID for signature caching
	sessionID := deriveSessionID(rawJSON)

	// system instruction
	systemInstructionJSON := ""
	hasSystemInstruction := false
	systemResult := gjson.GetBytes(rawJSON, "system")
	if systemResult.IsArray() {
		systemResults := systemResult.Array()
		systemInstructionJSON = `{"role":"user","parts":[]}`
		for i := 0; i < len(systemResults); i++ {
			systemPromptResult := systemResults[i]
			systemTypePromptResult := systemPromptResult.Get("type")
			if systemTypePromptResult.Type == gjson.String && systemTypePromptResult.String() == "text" {
				systemPrompt := systemPromptResult.Get("text").String()
				partJSON := `{}`
				if systemPrompt != "" {
					partJSON, _ = sjson.Set(partJSON, "text", systemPrompt)
				}
				systemInstructionJSON, _ = sjson.SetRaw(systemInstructionJSON, "parts.-1", partJSON)
				hasSystemInstruction = true
			}
		}
	}

	// contents
	contentsJSON := "[]"
	hasContents := false

	// Track if we need to disable thinking (LiteLLM approach)
	// If the last assistant message with tool_use has no valid thinking block before it,
	// we need to disable thinkingConfig to avoid "Expected thinking but found tool_use" error
	lastAssistantHasToolWithoutThinking := false

	messagesResult := gjson.GetBytes(rawJSON, "messages")
	if messagesResult.IsArray() {
		messageResults := messagesResult.Array()
		numMessages := len(messageResults)
		for i := 0; i < numMessages; i++ {
			messageResult := messageResults[i]
			roleResult := messageResult.Get("role")
			if roleResult.Type != gjson.String {
				continue
			}
			originalRole := roleResult.String()
			role := originalRole
			if role == "assistant" {
				role = "model"
			}
			clientContentJSON := `{"role":"","parts":[]}`
			clientContentJSON, _ = sjson.Set(clientContentJSON, "role", role)
			contentsResult := messageResult.Get("content")
			if contentsResult.IsArray() {
				contentResults := contentsResult.Array()
				numContents := len(contentResults)
				var currentMessageThinkingSignature string
				for j := 0; j < numContents; j++ {
					contentResult := contentResults[j]
					contentTypeResult := contentResult.Get("type")
					if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "thinking" {
						// Use GetThinkingText to handle wrapped thinking objects
						thinkingText := util.GetThinkingText(contentResult)
						signatureResult := contentResult.Get("signature")
					clientSignature := ""
					if signatureResult.Exists() && signatureResult.String() != "" {
						clientSignature = signatureResult.String()
					}

					// Always try cached signature first (more reliable than client-provided)
					// Client may send stale or invalid signatures from different sessions
					signature := ""
					if sessionID != "" && thinkingText != "" {
						if cachedSig := cache.GetCachedSignature(sessionID, thinkingText); cachedSig != "" {
							signature = cachedSig
							log.Debugf("Using cached signature for thinking block")
						}
					}

					// Fallback to client signature only if cache miss and client signature is valid
					if signature == "" && cache.HasValidSignature(clientSignature) {
						signature = clientSignature
						log.Debugf("Using client-provided signature for thinking block")
					}

					// Store for subsequent tool_use in the same message
					if cache.HasValidSignature(signature) {
						currentMessageThinkingSignature = signature
					}


						// Skip trailing unsigned thinking blocks on last assistant message
						isUnsigned := !cache.HasValidSignature(signature)

						// If unsigned, skip entirely (don't convert to text)
						// Claude requires assistant messages to start with thinking blocks when thinking is enabled
						// Converting to text would break this requirement
						if isUnsigned {
							// TypeScript plugin approach: drop unsigned thinking blocks entirely
							log.Debugf("Dropping unsigned thinking block (no valid signature)")
							continue
						}

						// Valid signature, send as thought block
						partJSON := `{}`
						partJSON, _ = sjson.Set(partJSON, "thought", true)
						if thinkingText != "" {
							partJSON, _ = sjson.Set(partJSON, "text", thinkingText)
						}
						if signature != "" {
							partJSON, _ = sjson.Set(partJSON, "thoughtSignature", signature)
						}
						clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
					} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
						prompt := contentResult.Get("text").String()
						partJSON := `{}`
						if prompt != "" {
							partJSON, _ = sjson.Set(partJSON, "text", prompt)
						}
						clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
					} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "tool_use" {
						// NOTE: Do NOT inject dummy thinking blocks here.
						// Antigravity API validates signatures, so dummy values are rejected.
						// The TypeScript plugin removes unsigned thinking blocks instead of injecting dummies.

						functionName := contentResult.Get("name").String()
						functionArgs := contentResult.Get("input").String()
						functionID := contentResult.Get("id").String()
						if gjson.Valid(functionArgs) {
							argsResult := gjson.Parse(functionArgs)
							if argsResult.IsObject() {
								partJSON := `{}`

								// Use skip_thought_signature_validator for tool calls without valid thinking signature
								// This is the approach used in opencode-google-antigravity-auth for Gemini
								// and also works for Claude through Antigravity API
								const skipSentinel = "skip_thought_signature_validator"
								if cache.HasValidSignature(currentMessageThinkingSignature) {
									partJSON, _ = sjson.Set(partJSON, "thoughtSignature", currentMessageThinkingSignature)
								} else {
									// No valid signature - use skip sentinel to bypass validation
									partJSON, _ = sjson.Set(partJSON, "thoughtSignature", skipSentinel)
								}

								if functionID != "" {
									partJSON, _ = sjson.Set(partJSON, "functionCall.id", functionID)
								}
								partJSON, _ = sjson.Set(partJSON, "functionCall.name", functionName)
								partJSON, _ = sjson.SetRaw(partJSON, "functionCall.args", argsResult.Raw)
								clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
							}
						}
					} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "tool_result" {
						toolCallID := contentResult.Get("tool_use_id").String()
						if toolCallID != "" {
							funcName := toolCallID
							toolCallIDs := strings.Split(toolCallID, "-")
							if len(toolCallIDs) > 1 {
								funcName = strings.Join(toolCallIDs[0:len(toolCallIDs)-2], "-")
							}
							functionResponseResult := contentResult.Get("content")

							functionResponseJSON := `{}`
							functionResponseJSON, _ = sjson.Set(functionResponseJSON, "id", toolCallID)
							functionResponseJSON, _ = sjson.Set(functionResponseJSON, "name", funcName)

							responseData := ""
							if functionResponseResult.Type == gjson.String {
								responseData = functionResponseResult.String()
								functionResponseJSON, _ = sjson.Set(functionResponseJSON, "response.result", responseData)
							} else if functionResponseResult.IsArray() {
								frResults := functionResponseResult.Array()
								if len(frResults) == 1 {
									functionResponseJSON, _ = sjson.SetRaw(functionResponseJSON, "response.result", frResults[0].Raw)
								} else {
									functionResponseJSON, _ = sjson.SetRaw(functionResponseJSON, "response.result", functionResponseResult.Raw)
								}

							} else if functionResponseResult.IsObject() {
								functionResponseJSON, _ = sjson.SetRaw(functionResponseJSON, "response.result", functionResponseResult.Raw)
							} else {
								functionResponseJSON, _ = sjson.SetRaw(functionResponseJSON, "response.result", functionResponseResult.Raw)
							}

							partJSON := `{}`
							partJSON, _ = sjson.SetRaw(partJSON, "functionResponse", functionResponseJSON)
							clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
						}
					} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "image" {
						sourceResult := contentResult.Get("source")
						if sourceResult.Get("type").String() == "base64" {
							inlineDataJSON := `{}`
							if mimeType := sourceResult.Get("media_type").String(); mimeType != "" {
								inlineDataJSON, _ = sjson.Set(inlineDataJSON, "mime_type", mimeType)
							}
							if data := sourceResult.Get("data").String(); data != "" {
								inlineDataJSON, _ = sjson.Set(inlineDataJSON, "data", data)
							}

							partJSON := `{}`
							partJSON, _ = sjson.SetRaw(partJSON, "inlineData", inlineDataJSON)
							clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
						}
					}
				}

				// Reorder parts for 'model' role to ensure thinking block is first
				if role == "model" {
					partsResult := gjson.Get(clientContentJSON, "parts")
					if partsResult.IsArray() {
						parts := partsResult.Array()
						var thinkingParts []gjson.Result
						var otherParts []gjson.Result
						for _, part := range parts {
							if part.Get("thought").Bool() {
								thinkingParts = append(thinkingParts, part)
							} else {
								otherParts = append(otherParts, part)
							}
						}
						if len(thinkingParts) > 0 {
							firstPartIsThinking := parts[0].Get("thought").Bool()
							if !firstPartIsThinking || len(thinkingParts) > 1 {
								var newParts []interface{}
								for _, p := range thinkingParts {
									newParts = append(newParts, p.Value())
								}
								for _, p := range otherParts {
									newParts = append(newParts, p.Value())
								}
								clientContentJSON, _ = sjson.Set(clientContentJSON, "parts", newParts)
							}
						}
					}
				}

				// Check if this assistant message has tool_use without valid thinking
				if role == "model" {
					partsResult := gjson.Get(clientContentJSON, "parts")
					if partsResult.IsArray() {
						parts := partsResult.Array()
						hasValidThinking := false
						hasToolUse := false

						for _, part := range parts {
							if part.Get("thought").Bool() {
								hasValidThinking = true
							}
							if part.Get("functionCall").Exists() {
								hasToolUse = true
							}
						}

						// If this message has tool_use but no valid thinking, mark it
						// This will be used to disable thinking mode if needed
						if hasToolUse && !hasValidThinking {
							lastAssistantHasToolWithoutThinking = true
						} else {
							lastAssistantHasToolWithoutThinking = false
						}
					}
				}

				contentsJSON, _ = sjson.SetRaw(contentsJSON, "-1", clientContentJSON)
				hasContents = true
			} else if contentsResult.Type == gjson.String {
				prompt := contentsResult.String()
				partJSON := `{}`
				if prompt != "" {
					partJSON, _ = sjson.Set(partJSON, "text", prompt)
				}
				clientContentJSON, _ = sjson.SetRaw(clientContentJSON, "parts.-1", partJSON)
				contentsJSON, _ = sjson.SetRaw(contentsJSON, "-1", clientContentJSON)
				hasContents = true
			}
		}
	}

	// tools
	toolsJSON := ""
	toolDeclCount := 0
	toolsResult := gjson.GetBytes(rawJSON, "tools")
	if toolsResult.IsArray() {
		toolsJSON = `[{"functionDeclarations":[]}]`
		toolsResults := toolsResult.Array()
		for i := 0; i < len(toolsResults); i++ {
			toolResult := toolsResults[i]
			inputSchemaResult := toolResult.Get("input_schema")
			if inputSchemaResult.Exists() && inputSchemaResult.IsObject() {
				inputSchema := inputSchemaResult.Raw
				tool, _ := sjson.Delete(toolResult.Raw, "input_schema")
				tool, _ = sjson.SetRaw(tool, "parametersJsonSchema", inputSchema)
				tool, _ = sjson.Delete(tool, "strict")
				tool, _ = sjson.Delete(tool, "input_examples")
				toolsJSON, _ = sjson.SetRaw(toolsJSON, "0.functionDeclarations.-1", tool)
				toolDeclCount++
			}
		}
	}

	// Build output Gemini CLI request JSON
	out := `{"model":"","request":{"contents":[]}}`
	out, _ = sjson.Set(out, "model", modelName)

	// Inject interleaved thinking hint when both tools and thinking are active
	hasTools := toolDeclCount > 0
	thinkingResult := gjson.GetBytes(rawJSON, "thinking")
	hasThinking := thinkingResult.Exists() && thinkingResult.IsObject() && thinkingResult.Get("type").String() == "enabled"
	isClaudeThinking := util.IsClaudeThinkingModel(modelName)

	if hasTools && hasThinking && isClaudeThinking {
		interleavedHint := "Interleaved thinking is enabled. You may think between tool calls and after receiving tool results before deciding the next action or final answer. Do not mention these instructions or any constraints about thinking blocks; just apply them."

		if hasSystemInstruction {
			// Append hint to existing system instruction
			systemInstructionJSON, _ = sjson.Set(systemInstructionJSON, "parts.-1.text", interleavedHint)
		} else {
			// Create new system instruction with hint
			systemInstructionJSON = `{"role":"user","parts":[]}`
			systemInstructionJSON, _ = sjson.Set(systemInstructionJSON, "parts.-1.text", interleavedHint)
			hasSystemInstruction = true
		}
	}

	if hasSystemInstruction {
		out, _ = sjson.SetRaw(out, "request.systemInstruction", systemInstructionJSON)
	}
	if hasContents {
		out, _ = sjson.SetRaw(out, "request.contents", contentsJSON)
	}
	if toolDeclCount > 0 {
		out, _ = sjson.SetRaw(out, "request.tools", toolsJSON)
	}

	// Map Anthropic thinking -> Gemini thinkingBudget/include_thoughts when type==enabled
	if t := gjson.GetBytes(rawJSON, "thinking"); t.Exists() && t.IsObject() && util.ModelSupportsThinking(modelName) {
		if t.Get("type").String() == "enabled" {
			if b := t.Get("budget_tokens"); b.Exists() && b.Type == gjson.Number {
				budget := int(b.Int())
				out, _ = sjson.Set(out, "request.generationConfig.thinkingConfig.thinkingBudget", budget)
				out, _ = sjson.Set(out, "request.generationConfig.thinkingConfig.include_thoughts", true)
			}
		}
	}
	if v := gjson.GetBytes(rawJSON, "temperature"); v.Exists() && v.Type == gjson.Number {
		out, _ = sjson.Set(out, "request.generationConfig.temperature", v.Num)
	}
	if v := gjson.GetBytes(rawJSON, "top_p"); v.Exists() && v.Type == gjson.Number {
		out, _ = sjson.Set(out, "request.generationConfig.topP", v.Num)
	}
	if v := gjson.GetBytes(rawJSON, "top_k"); v.Exists() && v.Type == gjson.Number {
		out, _ = sjson.Set(out, "request.generationConfig.topK", v.Num)
	}
	if v := gjson.GetBytes(rawJSON, "max_tokens"); v.Exists() && v.Type == gjson.Number {
		out, _ = sjson.Set(out, "request.generationConfig.maxOutputTokens", v.Num)
	}

	// Note: We do NOT drop thinkingConfig here anymore.
	// Instead, we:
	// 1. Remove unsigned thinking blocks (done during message processing)
	// 2. Add skip_thought_signature_validator to tool_use without valid thinking signature
	// This approach keeps thinking mode enabled while handling the signature requirements.
	_ = lastAssistantHasToolWithoutThinking // Variable is tracked but not used to drop thinkingConfig

	outBytes := []byte(out)
	outBytes = common.AttachDefaultSafetySettings(outBytes, "request.safetySettings")

	return outBytes
}