package executor

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

	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
	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"
)

// OpenAICompatExecutor implements a stateless executor for OpenAI-compatible providers.
// It performs request/response translation and executes against the provider base URL
// using per-auth credentials (API key) and per-auth HTTP transport (proxy) from context.
type OpenAICompatExecutor struct {
	provider string
	cfg      *config.Config
}

// NewOpenAICompatExecutor creates an executor bound to a provider key (e.g., "openrouter").
func NewOpenAICompatExecutor(provider string, cfg *config.Config) *OpenAICompatExecutor {
	return &OpenAICompatExecutor{provider: provider, cfg: cfg}
}

// Identifier implements cliproxyauth.ProviderExecutor.
func (e *OpenAICompatExecutor) Identifier() string { return e.provider }

// PrepareRequest is a no-op for now (credentials are added via headers at execution time).
func (e *OpenAICompatExecutor) PrepareRequest(_ *http.Request, _ *cliproxyauth.Auth) error {
	return nil
}

func (e *OpenAICompatExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
	baseURL, apiKey := e.resolveCredentials(auth)
	if baseURL == "" || apiKey == "" {
		return cliproxyexecutor.Response{}, statusErr{code: http.StatusUnauthorized, msg: "missing provider baseURL or apiKey"}
	}

	// Translate inbound request to OpenAI format
	from := opts.SourceFormat
	to := sdktranslator.FromString("openai")
	translated := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), opts.Stream)

	url := strings.TrimSuffix(baseURL, "/") + "/chat/completions"
	recordAPIRequest(ctx, e.cfg, translated)
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(translated))
	if err != nil {
		return cliproxyexecutor.Response{}, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("Authorization", "Bearer "+apiKey)
	httpReq.Header.Set("User-Agent", "cli-proxy-openai-compat")

	httpClient := &http.Client{}
	if rt, ok := ctx.Value("cliproxy.roundtripper").(http.RoundTripper); ok && rt != nil {
		httpClient.Transport = rt
	}
	resp, err := httpClient.Do(httpReq)
	if err != nil {
		return cliproxyexecutor.Response{}, err
	}
	defer func() { _ = resp.Body.Close() }()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		b, _ := io.ReadAll(resp.Body)
		appendAPIResponseChunk(ctx, e.cfg, b)
		return cliproxyexecutor.Response{}, statusErr{code: resp.StatusCode, msg: string(b)}
	}
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return cliproxyexecutor.Response{}, err
	}
	appendAPIResponseChunk(ctx, e.cfg, body)
	// Translate response back to source format when needed
	var param any
	out := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, body, &param)
	return cliproxyexecutor.Response{Payload: []byte(out)}, nil
}

func (e *OpenAICompatExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (<-chan cliproxyexecutor.StreamChunk, error) {
	baseURL, apiKey := e.resolveCredentials(auth)
	if baseURL == "" || apiKey == "" {
		return nil, statusErr{code: http.StatusUnauthorized, msg: "missing provider baseURL or apiKey"}
	}
	from := opts.SourceFormat
	to := sdktranslator.FromString("openai")
	translated := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), true)

	url := strings.TrimSuffix(baseURL, "/") + "/chat/completions"
	recordAPIRequest(ctx, e.cfg, translated)
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(translated))
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("Authorization", "Bearer "+apiKey)
	httpReq.Header.Set("User-Agent", "cli-proxy-openai-compat")
	httpReq.Header.Set("Accept", "text/event-stream")
	httpReq.Header.Set("Cache-Control", "no-cache")

	httpClient := &http.Client{Timeout: 0}
	if rt, ok := ctx.Value("cliproxy.roundtripper").(http.RoundTripper); ok && rt != nil {
		httpClient.Transport = rt
	}
	resp, err := httpClient.Do(httpReq)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		defer func() { _ = resp.Body.Close() }()
		b, _ := io.ReadAll(resp.Body)
		appendAPIResponseChunk(ctx, e.cfg, b)
		return nil, statusErr{code: resp.StatusCode, msg: string(b)}
	}
	out := make(chan cliproxyexecutor.StreamChunk)
	go func() {
		defer close(out)
		defer func() { _ = resp.Body.Close() }()
		scanner := bufio.NewScanner(resp.Body)
		buf := make([]byte, 1024*1024)
		scanner.Buffer(buf, 1024*1024)
		var param any
		for scanner.Scan() {
			line := scanner.Bytes()
			appendAPIResponseChunk(ctx, e.cfg, line)
			if len(line) == 0 {
				continue
			}
			// OpenAI-compatible streams are SSE: lines typically prefixed with "data: ".
			// Pass through translator; it yields one or more chunks for the target schema.
			chunks := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, bytes.Clone(line), &param)
			for i := range chunks {
				out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunks[i])}
			}
		}
		if err = scanner.Err(); err != nil {
			out <- cliproxyexecutor.StreamChunk{Err: err}
		}
	}()
	return out, nil
}

// Refresh is a no-op for API-key based compatibility providers.
func (e *OpenAICompatExecutor) Refresh(ctx context.Context, auth *cliproxyauth.Auth) (*cliproxyauth.Auth, error) {
	log.Debugf("openai compat executor: refresh called")
	_ = ctx
	return auth, nil
}

func (e *OpenAICompatExecutor) resolveCredentials(auth *cliproxyauth.Auth) (baseURL, apiKey string) {
	if auth == nil {
		return "", ""
	}
	if auth.Attributes != nil {
		baseURL = auth.Attributes["base_url"]
		apiKey = auth.Attributes["api_key"]
	}
	return
}

type statusErr struct {
	code int
	msg  string
}

func (e statusErr) Error() string {
	if e.msg != "" {
		return e.msg
	}
	return fmt.Sprintf("status %d", e.code)
}
func (e statusErr) StatusCode() int { return e.code }