// Package executor provides runtime execution capabilities for various AI service providers.
// It includes stateless executors that handle API requests, streaming responses,
// token counting, and authentication refresh for different AI service providers.
package executor

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

	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
	log "github.com/sirupsen/logrus"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
)

const (
	// glEndpoint is the base URL for the Google Generative Language API.
	glEndpoint = "https://generativelanguage.googleapis.com"

	// glAPIVersion is the API version used for Gemini requests.
	glAPIVersion = "v1beta"

	// streamScannerBuffer is the buffer size for SSE stream scanning.
	streamScannerBuffer = 52_428_800
)

// GeminiExecutor is a stateless executor for the official Gemini API using API keys.
// It handles both API key and OAuth bearer token authentication, supporting both
// regular and streaming requests to the Google Generative Language API.
type GeminiExecutor struct {
	// cfg holds the application configuration.
	cfg *config.Config
}

// NewGeminiExecutor creates a new Gemini executor instance.
//
// Parameters:
//   - cfg: The application configuration
//
// Returns:
//   - *GeminiExecutor: A new Gemini executor instance
func NewGeminiExecutor(cfg *config.Config) *GeminiExecutor {
	return &GeminiExecutor{cfg: cfg}
}

// Identifier returns the executor identifier.
func (e *GeminiExecutor) Identifier() string { return "gemini" }

// PrepareRequest prepares the HTTP request for execution (no-op for Gemini).
func (e *GeminiExecutor) PrepareRequest(_ *http.Request, _ *cliproxyauth.Auth) error { return nil }

// Execute performs a non-streaming request to the Gemini API.
// It translates the request to Gemini format, sends it to the API, and translates
// the response back to the requested format.
//
// Parameters:
//   - ctx: The context for the request
//   - auth: The authentication information
//   - req: The request to execute
//   - opts: Additional execution options
//
// Returns:
//   - cliproxyexecutor.Response: The response from the API
//   - error: An error if the request fails
func (e *GeminiExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (resp cliproxyexecutor.Response, err error) {
	apiKey, bearer := geminiCreds(auth)

	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
	defer reporter.trackFailure(ctx, &err)

	model := req.Model
	if override := e.resolveUpstreamModel(model, auth); override != "" {
		model = override
	}

	// Official Gemini API via API key or OAuth bearer
	from := opts.SourceFormat
	to := sdktranslator.FromString("gemini")
	originalPayload := bytes.Clone(req.Payload)
	if len(opts.OriginalRequest) > 0 {
		originalPayload = bytes.Clone(opts.OriginalRequest)
	}
	originalTranslated := sdktranslator.TranslateRequest(from, to, model, originalPayload, false)
	body := sdktranslator.TranslateRequest(from, to, model, bytes.Clone(req.Payload), false)
	body = ApplyThinkingMetadata(body, req.Metadata, model)
	body = util.ApplyDefaultThinkingIfNeeded(model, body)
	body = util.NormalizeGeminiThinkingBudget(model, body)
	body = util.StripThinkingConfigIfUnsupported(model, body)
	body = fixGeminiImageAspectRatio(model, body)
	body = applyPayloadConfigWithRoot(e.cfg, model, to.String(), "", body, originalTranslated)
	body, _ = sjson.SetBytes(body, "model", model)

	action := "generateContent"
	if req.Metadata != nil {
		if a, _ := req.Metadata["action"].(string); a == "countTokens" {
			action = "countTokens"
		}
	}
	baseURL := resolveGeminiBaseURL(auth)
	url := fmt.Sprintf("%s/%s/models/%s:%s", baseURL, glAPIVersion, model, action)
	if opts.Alt != "" && action != "countTokens" {
		url = url + fmt.Sprintf("?$alt=%s", opts.Alt)
	}

	body, _ = sjson.DeleteBytes(body, "session_id")

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return resp, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	if apiKey != "" {
		httpReq.Header.Set("x-goog-api-key", apiKey)
	} else if bearer != "" {
		httpReq.Header.Set("Authorization", "Bearer "+bearer)
	}
	applyGeminiHeaders(httpReq, auth)
	var authID, authLabel, authType, authValue string
	if auth != nil {
		authID = auth.ID
		authLabel = auth.Label
		authType, authValue = auth.AccountInfo()
	}
	recordAPIRequest(ctx, e.cfg, upstreamRequestLog{
		URL:       url,
		Method:    http.MethodPost,
		Headers:   httpReq.Header.Clone(),
		Body:      body,
		Provider:  e.Identifier(),
		AuthID:    authID,
		AuthLabel: authLabel,
		AuthType:  authType,
		AuthValue: authValue,
	})

	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
	httpResp, err := httpClient.Do(httpReq)
	if err != nil {
		recordAPIResponseError(ctx, e.cfg, err)
		return resp, err
	}
	defer func() {
		if errClose := httpResp.Body.Close(); errClose != nil {
			log.Errorf("gemini executor: close response body error: %v", errClose)
		}
	}()
	recordAPIResponseMetadata(ctx, e.cfg, httpResp.StatusCode, httpResp.Header.Clone())
	if httpResp.StatusCode < 200 || httpResp.StatusCode >= 300 {
		b, _ := io.ReadAll(httpResp.Body)
		appendAPIResponseChunk(ctx, e.cfg, b)
		log.Warnf("gemini executor: upstream API error, status: %d, body: %s", httpResp.StatusCode, summarizeErrorBody(httpResp.Header.Get("Content-Type"), b))
		err = statusErr{code: httpResp.StatusCode, msg: string(b)}
		return resp, err
	}
	data, err := io.ReadAll(httpResp.Body)
	if err != nil {
		recordAPIResponseError(ctx, e.cfg, err)
		return resp, err
	}
	appendAPIResponseChunk(ctx, e.cfg, data)
	reporter.publish(ctx, parseGeminiUsage(data))
	var param any
	out := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, data, &param)
	resp = cliproxyexecutor.Response{Payload: []byte(out)}
	return resp, nil
}

// ExecuteStream performs a streaming request to the Gemini API.
func (e *GeminiExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (stream <-chan cliproxyexecutor.StreamChunk, err error) {
	apiKey, bearer := geminiCreds(auth)

	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
	defer reporter.trackFailure(ctx, &err)

	model := req.Model
	if override := e.resolveUpstreamModel(model, auth); override != "" {
		model = override
	}

	from := opts.SourceFormat
	to := sdktranslator.FromString("gemini")
	originalPayload := bytes.Clone(req.Payload)
	if len(opts.OriginalRequest) > 0 {
		originalPayload = bytes.Clone(opts.OriginalRequest)
	}
	originalTranslated := sdktranslator.TranslateRequest(from, to, model, originalPayload, true)
	body := sdktranslator.TranslateRequest(from, to, model, bytes.Clone(req.Payload), true)
	body = ApplyThinkingMetadata(body, req.Metadata, model)
	body = util.ApplyDefaultThinkingIfNeeded(model, body)
	body = util.NormalizeGeminiThinkingBudget(model, body)
	body = util.StripThinkingConfigIfUnsupported(model, body)
	body = fixGeminiImageAspectRatio(model, body)
	body = applyPayloadConfigWithRoot(e.cfg, model, to.String(), "", body, originalTranslated)
	body, _ = sjson.SetBytes(body, "model", model)

	baseURL := resolveGeminiBaseURL(auth)
	url := fmt.Sprintf("%s/%s/models/%s:%s", baseURL, glAPIVersion, model, "streamGenerateContent")
	if opts.Alt == "" {
		url = url + "?alt=sse"
	} else {
		url = url + fmt.Sprintf("?$alt=%s", opts.Alt)
	}

	body, _ = sjson.DeleteBytes(body, "session_id")

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	if apiKey != "" {
		httpReq.Header.Set("x-goog-api-key", apiKey)
	} else {
		httpReq.Header.Set("Authorization", "Bearer "+bearer)
	}
	applyGeminiHeaders(httpReq, auth)
	var authID, authLabel, authType, authValue string
	if auth != nil {
		authID = auth.ID
		authLabel = auth.Label
		authType, authValue = auth.AccountInfo()
	}
	recordAPIRequest(ctx, e.cfg, upstreamRequestLog{
		URL:       url,
		Method:    http.MethodPost,
		Headers:   httpReq.Header.Clone(),
		Body:      body,
		Provider:  e.Identifier(),
		AuthID:    authID,
		AuthLabel: authLabel,
		AuthType:  authType,
		AuthValue: authValue,
	})

	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
	httpResp, err := httpClient.Do(httpReq)
	if err != nil {
		recordAPIResponseError(ctx, e.cfg, err)
		return nil, err
	}
	recordAPIResponseMetadata(ctx, e.cfg, httpResp.StatusCode, httpResp.Header.Clone())
	if httpResp.StatusCode < 200 || httpResp.StatusCode >= 300 {
		b, _ := io.ReadAll(httpResp.Body)
		appendAPIResponseChunk(ctx, e.cfg, b)
		log.Warnf("gemini executor: upstream API error (stream), status: %d, body: %s", httpResp.StatusCode, summarizeErrorBody(httpResp.Header.Get("Content-Type"), b))
		return nil, statusErr{code: httpResp.StatusCode, msg: string(b)}
	}
	out := make(chan cliproxyexecutor.StreamChunk)
	stream = out
	go func() {
		defer close(out)
		defer func() {
			if errClose := httpResp.Body.Close(); errClose != nil {
				log.Errorf("gemini executor: close response body error: %v", errClose)
			}
		}()
		scanner := bufio.NewScanner(httpResp.Body)
		scanner.Buffer(nil, streamScannerBuffer)
		var param any
		for scanner.Scan() {
			line := scanner.Bytes()
			appendAPIResponseChunk(ctx, e.cfg, line)
			filtered := FilterSSEUsageMetadata(line)
			payload := jsonPayload(filtered)
			if len(payload) == 0 {
				continue
			}
			if detail, ok := parseGeminiStreamUsage(payload); ok {
				reporter.publish(ctx, detail)
			}
			lines := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, bytes.Clone(payload), &param)
			for i := range lines {
				out <- cliproxyexecutor.StreamChunk{Payload: []byte(lines[i])}
			}
		}
		lines := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, bytes.Clone([]byte("[DONE]")), &param)
		for i := range lines {
			out <- cliproxyexecutor.StreamChunk{Payload: []byte(lines[i])}
		}
		if errScan := scanner.Err(); errScan != nil {
			recordAPIResponseError(ctx, e.cfg, errScan)
			reporter.publishFailure(ctx)
			out <- cliproxyexecutor.StreamChunk{Err: errScan}
		}
	}()
	return stream, nil
}

// CountTokens counts tokens for the given request using the Gemini API.
func (e *GeminiExecutor) CountTokens(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
	apiKey, bearer := geminiCreds(auth)

	model := req.Model
	if override := e.resolveUpstreamModel(model, auth); override != "" {
		model = override
	}

	from := opts.SourceFormat
	to := sdktranslator.FromString("gemini")
	translatedReq := sdktranslator.TranslateRequest(from, to, model, bytes.Clone(req.Payload), false)
	translatedReq = ApplyThinkingMetadata(translatedReq, req.Metadata, model)
	translatedReq = util.StripThinkingConfigIfUnsupported(model, translatedReq)
	translatedReq = fixGeminiImageAspectRatio(model, translatedReq)
	respCtx := context.WithValue(ctx, "alt", opts.Alt)
	translatedReq, _ = sjson.DeleteBytes(translatedReq, "tools")
	translatedReq, _ = sjson.DeleteBytes(translatedReq, "generationConfig")
	translatedReq, _ = sjson.DeleteBytes(translatedReq, "safetySettings")
	translatedReq, _ = sjson.SetBytes(translatedReq, "model", model)

	baseURL := resolveGeminiBaseURL(auth)
	url := fmt.Sprintf("%s/%s/models/%s:%s", baseURL, glAPIVersion, model, "countTokens")

	requestBody := bytes.NewReader(translatedReq)

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, requestBody)
	if err != nil {
		return cliproxyexecutor.Response{}, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	if apiKey != "" {
		httpReq.Header.Set("x-goog-api-key", apiKey)
	} else {
		httpReq.Header.Set("Authorization", "Bearer "+bearer)
	}
	applyGeminiHeaders(httpReq, auth)
	var authID, authLabel, authType, authValue string
	if auth != nil {
		authID = auth.ID
		authLabel = auth.Label
		authType, authValue = auth.AccountInfo()
	}
	recordAPIRequest(ctx, e.cfg, upstreamRequestLog{
		URL:       url,
		Method:    http.MethodPost,
		Headers:   httpReq.Header.Clone(),
		Body:      translatedReq,
		Provider:  e.Identifier(),
		AuthID:    authID,
		AuthLabel: authLabel,
		AuthType:  authType,
		AuthValue: authValue,
	})

	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
	resp, err := httpClient.Do(httpReq)
	if err != nil {
		recordAPIResponseError(ctx, e.cfg, err)
		return cliproxyexecutor.Response{}, err
	}
	defer func() { _ = resp.Body.Close() }()
	recordAPIResponseMetadata(ctx, e.cfg, resp.StatusCode, resp.Header.Clone())

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		recordAPIResponseError(ctx, e.cfg, err)
		return cliproxyexecutor.Response{}, err
	}
	appendAPIResponseChunk(ctx, e.cfg, data)
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		log.Warnf("gemini executor: upstream API error, status: %d, body: %s", resp.StatusCode, summarizeErrorBody(resp.Header.Get("Content-Type"), data))
		return cliproxyexecutor.Response{}, statusErr{code: resp.StatusCode, msg: string(data)}
	}

	count := gjson.GetBytes(data, "totalTokens").Int()
	translated := sdktranslator.TranslateTokenCount(respCtx, to, from, count, data)
	return cliproxyexecutor.Response{Payload: []byte(translated)}, nil
}

// Refresh refreshes the authentication credentials (no-op for Gemini API key).
func (e *GeminiExecutor) Refresh(_ context.Context, auth *cliproxyauth.Auth) (*cliproxyauth.Auth, error) {
	return auth, nil
}

func geminiCreds(a *cliproxyauth.Auth) (apiKey, bearer string) {
	if a == nil {
		return "", ""
	}
	if a.Attributes != nil {
		if v := a.Attributes["api_key"]; v != "" {
			apiKey = v
		}
	}
	if a.Metadata != nil {
		// GeminiTokenStorage.Token is a map that may contain access_token
		if v, ok := a.Metadata["access_token"].(string); ok && v != "" {
			bearer = v
		}
		if token, ok := a.Metadata["token"].(map[string]any); ok && token != nil {
			if v, ok2 := token["access_token"].(string); ok2 && v != "" {
				bearer = v
			}
		}
	}
	return
}

func resolveGeminiBaseURL(auth *cliproxyauth.Auth) string {
	base := glEndpoint
	if auth != nil && auth.Attributes != nil {
		if custom := strings.TrimSpace(auth.Attributes["base_url"]); custom != "" {
			base = strings.TrimRight(custom, "/")
		}
	}
	if base == "" {
		return glEndpoint
	}
	return base
}

func (e *GeminiExecutor) resolveUpstreamModel(alias string, auth *cliproxyauth.Auth) string {
	trimmed := strings.TrimSpace(alias)
	if trimmed == "" {
		return ""
	}

	entry := e.resolveGeminiConfig(auth)
	if entry == nil {
		return ""
	}

	normalizedModel, metadata := util.NormalizeThinkingModel(trimmed)

	// Candidate names to match against configured aliases/names.
	candidates := []string{strings.TrimSpace(normalizedModel)}
	if !strings.EqualFold(normalizedModel, trimmed) {
		candidates = append(candidates, trimmed)
	}
	if original := util.ResolveOriginalModel(normalizedModel, metadata); original != "" && !strings.EqualFold(original, normalizedModel) {
		candidates = append(candidates, original)
	}

	for i := range entry.Models {
		model := entry.Models[i]
		name := strings.TrimSpace(model.Name)
		modelAlias := strings.TrimSpace(model.Alias)

		for _, candidate := range candidates {
			if candidate == "" {
				continue
			}
			if modelAlias != "" && strings.EqualFold(modelAlias, candidate) {
				if name != "" {
					return name
				}
				return candidate
			}
			if name != "" && strings.EqualFold(name, candidate) {
				return name
			}
		}
	}
	return ""
}

func (e *GeminiExecutor) resolveGeminiConfig(auth *cliproxyauth.Auth) *config.GeminiKey {
	if auth == nil || e.cfg == nil {
		return nil
	}
	var attrKey, attrBase string
	if auth.Attributes != nil {
		attrKey = strings.TrimSpace(auth.Attributes["api_key"])
		attrBase = strings.TrimSpace(auth.Attributes["base_url"])
	}
	for i := range e.cfg.GeminiKey {
		entry := &e.cfg.GeminiKey[i]
		cfgKey := strings.TrimSpace(entry.APIKey)
		cfgBase := strings.TrimSpace(entry.BaseURL)
		if attrKey != "" && attrBase != "" {
			if strings.EqualFold(cfgKey, attrKey) && strings.EqualFold(cfgBase, attrBase) {
				return entry
			}
			continue
		}
		if attrKey != "" && strings.EqualFold(cfgKey, attrKey) {
			if cfgBase == "" || strings.EqualFold(cfgBase, attrBase) {
				return entry
			}
		}
		if attrKey == "" && attrBase != "" && strings.EqualFold(cfgBase, attrBase) {
			return entry
		}
	}
	if attrKey != "" {
		for i := range e.cfg.GeminiKey {
			entry := &e.cfg.GeminiKey[i]
			if strings.EqualFold(strings.TrimSpace(entry.APIKey), attrKey) {
				return entry
			}
		}
	}
	return nil
}

func applyGeminiHeaders(req *http.Request, auth *cliproxyauth.Auth) {
	var attrs map[string]string
	if auth != nil {
		attrs = auth.Attributes
	}
	util.ApplyCustomHeadersFromAttrs(req, attrs)
}

func fixGeminiImageAspectRatio(modelName string, rawJSON []byte) []byte {
	if modelName == "gemini-2.5-flash-image-preview" {
		aspectRatioResult := gjson.GetBytes(rawJSON, "generationConfig.imageConfig.aspectRatio")
		if aspectRatioResult.Exists() {
			contents := gjson.GetBytes(rawJSON, "contents")
			contentArray := contents.Array()
			if len(contentArray) > 0 {
				hasInlineData := false
			loopContent:
				for i := 0; i < len(contentArray); i++ {
					parts := contentArray[i].Get("parts").Array()
					for j := 0; j < len(parts); j++ {
						if parts[j].Get("inlineData").Exists() {
							hasInlineData = true
							break loopContent
						}
					}
				}

				if !hasInlineData {
					emptyImageBase64ed, _ := util.CreateWhiteImageBase64(aspectRatioResult.String())
					emptyImagePart := `{"inlineData":{"mime_type":"image/png","data":""}}`
					emptyImagePart, _ = sjson.Set(emptyImagePart, "inlineData.data", emptyImageBase64ed)
					newPartsJson := `[]`
					newPartsJson, _ = sjson.SetRaw(newPartsJson, "-1", `{"text": "Based on the following requirements, create an image within the uploaded picture. The new content *MUST* completely cover the entire area of the original picture, maintaining its exact proportions, and *NO* blank areas should appear."}`)
					newPartsJson, _ = sjson.SetRaw(newPartsJson, "-1", emptyImagePart)

					parts := contentArray[0].Get("parts").Array()
					for j := 0; j < len(parts); j++ {
						newPartsJson, _ = sjson.SetRaw(newPartsJson, "-1", parts[j].Raw)
					}

					rawJSON, _ = sjson.SetRawBytes(rawJSON, "contents.0.parts", []byte(newPartsJson))
					rawJSON, _ = sjson.SetRawBytes(rawJSON, "generationConfig.responseModalities", []byte(`["IMAGE", "TEXT"]`))
				}
			}
			rawJSON, _ = sjson.DeleteBytes(rawJSON, "generationConfig.imageConfig")
		}
	}
	return rawJSON
}