package executor

import (
	"bytes"
	"context"
	"fmt"
	"net/http"
	"strings"

	"github.com/router-for-me/CLIProxyAPI/v8/internal/runtime/executor/helps"
	"github.com/router-for-me/CLIProxyAPI/v8/internal/thinking"
	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/auth"
	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/executor"
	sdktranslator "github.com/router-for-me/CLIProxyAPI/v8/sdk/translator"
	log "github.com/sirupsen/logrus"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
)

type claudeCompactionSummaryContextKey struct{}

// expandClaudeResponsesCompaction rewrites sealed compaction items into context
// before translation. Unrecognized capsules fail the request instead of being dropped.
func expandClaudeResponsesCompaction(req *cliproxyexecutor.Request, opts *cliproxyexecutor.Options) error {
	if req != nil {
		req.Payload = dropForeignClaudeCompactionItems(req.Payload)
		if helps.HasResponsesCompactionItem(req.Payload) {
			expanded, errExpand := helps.ExpandAntigravityCompactionCapsules(req.Payload)
			if errExpand != nil {
				return errExpand
			}
			req.Payload = expanded
		}
	}
	if opts != nil {
		opts.OriginalRequest = dropForeignClaudeCompactionItems(opts.OriginalRequest)
		if helps.HasResponsesCompactionItem(opts.OriginalRequest) {
			expanded, errExpand := helps.ExpandAntigravityCompactionCapsules(opts.OriginalRequest)
			if errExpand != nil {
				return errExpand
			}
			opts.OriginalRequest = expanded
		}
	}
	return nil
}

func dropForeignClaudeCompactionItems(payload []byte) []byte {
	input := gjson.GetBytes(payload, "input")
	if !input.IsArray() {
		return payload
	}
	dropped := 0
	items := make([]string, 0, len(input.Array()))
	for _, item := range input.Array() {
		if item.Get("type").String() == "compaction" && !helps.RecognizedAntigravityCompactionCapsule(item.Get("encrypted_content").String()) {
			dropped++
			continue
		}
		items = append(items, item.Raw)
	}
	if dropped == 0 {
		return payload
	}
	log.Warnf("claude compaction: dropped %d non-CPA compaction item(s)", dropped)
	out, _ := sjson.SetRawBytes(payload, "input", []byte("["+strings.Join(items, ",")+"]"))
	return out
}

func claudeResponsesCompactionRequested(req cliproxyexecutor.Request, opts cliproxyexecutor.Options) bool {
	return opts.Alt == "responses/compact" ||
		helps.HasResponsesCompactionTrigger(req.Payload) ||
		helps.HasResponsesCompactionTrigger(opts.OriginalRequest)
}

func claudeCompactionSourcePayload(req cliproxyexecutor.Request, opts cliproxyexecutor.Options) []byte {
	payload := req.Payload
	if !helps.HasResponsesCompactionTrigger(payload) && helps.HasResponsesCompactionTrigger(opts.OriginalRequest) {
		payload = opts.OriginalRequest
	}
	if len(payload) == 0 && len(opts.OriginalRequest) > 0 {
		payload = opts.OriginalRequest
	}
	return payload
}

func (e *ClaudeExecutor) executeClaudeCompaction(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
	var resp cliproxyexecutor.Response
	baseModel := thinking.ParseSuffix(req.Model).ModelName
	summaryPayload := prepareClaudeCompactionSummaryPayload(claudeCompactionSourcePayload(req, opts), baseModel)
	summaryReq := cliproxyexecutor.Request{
		Model:    req.Model,
		Payload:  summaryPayload,
		Metadata: req.Metadata,
	}
	summaryOpts := opts
	summaryOpts.Alt = ""
	summaryOpts.Stream = false
	summaryOpts.OriginalRequest = nil
	summaryOpts.SourceFormat = sdktranslator.FormatOpenAIResponse
	summaryOpts.ResponseFormat = sdktranslator.FormatClaude

	summaryResp, errSummary := e.Execute(withClaudeCompactionSummary(ctx), auth, summaryReq, summaryOpts)
	if errSummary != nil {
		return resp, errSummary
	}
	summaryText, errExtract := helps.ExtractAntigravitySummaryText(summaryResp.Payload)
	if errExtract != nil {
		return resp, fmt.Errorf("extract summary: %w", errExtract)
	}
	capsule, errSeal := helps.SealAntigravityCompaction(summaryText, baseModel)
	if errSeal != nil {
		return resp, fmt.Errorf("seal compaction capsule: %w", errSeal)
	}

	inputTokens, outputTokens, totalTokens, cachedTokens := claudeCompactionResponsesUsage(summaryResp.Payload)
	respPayload := helps.BuildAntigravityCompactionResponse(baseModel, capsule, inputTokens, outputTokens, totalTokens)
	respPayload, _ = sjson.SetBytes(respPayload, "usage.input_tokens_details.cached_tokens", cachedTokens)
	return cliproxyexecutor.Response{
		Payload: respPayload,
		Headers: summaryResp.Headers,
	}, nil
}

func (e *ClaudeExecutor) executeClaudeCompactionStream(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (*cliproxyexecutor.StreamResult, error) {
	baseModel := thinking.ParseSuffix(req.Model).ModelName
	summaryResp, errSummary := e.executeClaudeCompaction(ctx, auth, req, opts)
	if errSummary != nil {
		return nil, errSummary
	}
	// Reuse the capsule and usage already sealed for the non-stream response.
	item := gjson.GetBytes(summaryResp.Payload, "output.0")
	capsule := item.Get("encrypted_content").String()
	if item.Get("type").String() != "compaction" || capsule == "" {
		return nil, fmt.Errorf("extract summary: compaction item missing")
	}
	inputTokens := int(gjson.GetBytes(summaryResp.Payload, "usage.input_tokens").Int())
	outputTokens := int(gjson.GetBytes(summaryResp.Payload, "usage.output_tokens").Int())
	totalTokens := int(gjson.GetBytes(summaryResp.Payload, "usage.total_tokens").Int())
	cachedTokens := int(gjson.GetBytes(summaryResp.Payload, "usage.input_tokens_details.cached_tokens").Int())
	chunks := helps.BuildAntigravityCompactionStreamChunks(baseModel, capsule, inputTokens, outputTokens, totalTokens)
	for i := range chunks {
		chunks[i] = patchClaudeCompactionStreamUsage(chunks[i], inputTokens, outputTokens, totalTokens, cachedTokens)
	}
	out := make(chan cliproxyexecutor.StreamChunk, len(chunks))
	for _, chunk := range chunks {
		out <- cliproxyexecutor.StreamChunk{Payload: chunk}
	}
	close(out)

	headers := summaryResp.Headers.Clone()
	if headers == nil {
		headers = make(http.Header)
	}
	headers.Set("Content-Type", "text/event-stream")
	return &cliproxyexecutor.StreamResult{Headers: headers, Chunks: out}, nil
}

func withClaudeCompactionSummary(ctx context.Context) context.Context {
	if ctx == nil {
		ctx = context.Background()
	}
	return context.WithValue(ctx, claudeCompactionSummaryContextKey{}, true)
}

func claudeCompactionSummaryFromContext(ctx context.Context) bool {
	if ctx == nil {
		return false
	}
	flag, ok := ctx.Value(claudeCompactionSummaryContextKey{}).(bool)
	return ok && flag
}

// prepareClaudeCompactionSummaryPayload keeps tool definitions that Claude needs
// in order to accept tool_use history, while still asking for a text summary.
func prepareClaudeCompactionSummaryPayload(payload []byte, modelName string) []byte {
	tools := gjson.GetBytes(payload, "tools")
	additionalTools := gjson.GetBytes(payload, "additional_tools")
	out := helps.PrepareAntigravityCompactionSummaryPayload(payload, modelName)
	if tools.Exists() {
		out, _ = sjson.SetRawBytes(out, "tools", []byte(tools.Raw))
	}
	if additionalTools.Exists() {
		out, _ = sjson.SetRawBytes(out, "additional_tools", []byte(additionalTools.Raw))
	}
	return out
}

// finalizeClaudeCompactionSummaryBody runs after built-in translation and before
// user payload rules. Tool history stays structured when definitions exist, and
// tool_choice none stops the summary turn from calling a tool. History without
// definitions is flattened so Anthropic does not reject orphan tool blocks.
func finalizeClaudeCompactionSummaryBody(body []byte) []byte {
	if claudeBodyHasToolDefinitions(body) {
		body, _ = sjson.SetRawBytes(body, "tool_choice", []byte(`{"type":"none"}`))
		return body
	}
	return flattenClaudeToolBlocksForCompaction(body)
}

func claudeBodyHasToolDefinitions(body []byte) bool {
	tools := gjson.GetBytes(body, "tools")
	return tools.IsArray() && len(tools.Array()) > 0
}

func flattenClaudeToolBlocksForCompaction(body []byte) []byte {
	messages := gjson.GetBytes(body, "messages")
	if !messages.IsArray() {
		return body
	}
	changed := false
	rewritten := make([]string, 0, len(messages.Array()))
	for _, msg := range messages.Array() {
		content := msg.Get("content")
		if !content.IsArray() {
			rewritten = append(rewritten, msg.Raw)
			continue
		}
		parts := make([]string, 0, len(content.Array()))
		msgChanged := false
		for _, part := range content.Array() {
			switch part.Get("type").String() {
			case "tool_use":
				text := fmt.Sprintf("Tool call %s (%s): %s", part.Get("name").String(), part.Get("id").String(), part.Get("input").Raw)
				block, _ := sjson.SetBytes([]byte(`{"type":"text","text":""}`), "text", text)
				parts = append(parts, string(block))
				msgChanged = true
			case "tool_result":
				result := part.Get("content")
				resultText := result.Raw
				if result.Type == gjson.String {
					resultText = result.String()
				}
				text := fmt.Sprintf("Tool result %s: %s", part.Get("tool_use_id").String(), resultText)
				block, _ := sjson.SetBytes([]byte(`{"type":"text","text":""}`), "text", text)
				parts = append(parts, string(block))
				msgChanged = true
			default:
				parts = append(parts, part.Raw)
			}
		}
		if !msgChanged {
			rewritten = append(rewritten, msg.Raw)
			continue
		}
		changed = true
		updated, _ := sjson.SetRawBytes([]byte(msg.Raw), "content", []byte("["+strings.Join(parts, ",")+"]"))
		rewritten = append(rewritten, string(updated))
	}
	if !changed {
		return body
	}
	body, _ = sjson.SetRawBytes(body, "messages", []byte("["+strings.Join(rewritten, ",")+"]"))
	return body
}

// claudeCompactionResponsesUsage matches the Responses translator: input includes
// cache creation and cache read, cached_tokens is cache read, and total is their sum.
func claudeCompactionResponsesUsage(payload []byte) (inputTokens, outputTokens, totalTokens, cachedTokens int) {
	usage := gjson.GetBytes(payload, "usage")
	if !usage.Exists() {
		parsed := helps.ParseOpenAIUsage(payload)
		return int(parsed.InputTokens), int(parsed.OutputTokens), int(parsed.TotalTokens), 0
	}
	rawInput := int(usage.Get("input_tokens").Int())
	outputTokens = int(usage.Get("output_tokens").Int())
	cacheCreation := int(usage.Get("cache_creation_input_tokens").Int())
	cachedTokens = int(usage.Get("cache_read_input_tokens").Int())
	inputTokens = rawInput + cacheCreation + cachedTokens
	totalTokens = inputTokens + outputTokens
	return inputTokens, outputTokens, totalTokens, cachedTokens
}

func patchClaudeCompactionStreamUsage(chunk []byte, inputTokens, outputTokens, totalTokens, cachedTokens int) []byte {
	const dataPrefix = "data: "
	idx := bytes.Index(chunk, []byte(dataPrefix))
	if idx < 0 {
		return chunk
	}
	data := bytes.TrimSpace(chunk[idx+len(dataPrefix):])
	path := ""
	switch {
	case gjson.GetBytes(data, "response.usage").Exists():
		path = "response.usage"
	case gjson.GetBytes(data, "usage").Exists():
		path = "usage"
	default:
		return chunk
	}
	data, _ = sjson.SetBytes(data, path+".input_tokens", inputTokens)
	data, _ = sjson.SetBytes(data, path+".output_tokens", outputTokens)
	data, _ = sjson.SetBytes(data, path+".total_tokens", totalTokens)
	data, _ = sjson.SetBytes(data, path+".input_tokens_details.cached_tokens", cachedTokens)
	var buf bytes.Buffer
	buf.Write(chunk[:idx])
	buf.WriteString(dataPrefix)
	buf.Write(data)
	buf.WriteString("\n\n")
	return buf.Bytes()
}