package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"flag"
	"io"
	"log/slog"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"grailbench/config"
	"grailbench/models"
)

var (
	logger     *slog.Logger
	cfg        *config.Config
	httpClient = &http.Client{}
)

func loadQuestions(fp string) ([]models.Question, error) {
	data, err := os.ReadFile(fp)
	if err != nil {
		logger.Error("failed to read file", "error", err, "fp", fp)
		return nil, err
	}
	resp := []models.Question{}
	if err := json.Unmarshal(data, &resp); err != nil {
		logger.Error("failed to unmarshal file", "error", err, "fp", fp)
		return nil, err
	}
	return resp, nil
}

func loadRPScenarios(dir string) ([]*models.RPScenario, error) {
	scenarios := []*models.RPScenario{}
	files, err := os.ReadDir(dir)
	if err != nil {
		return nil, err
	}
	for _, file := range files {
		if !file.IsDir() && strings.HasSuffix(file.Name(), ".json") {
			fp := filepath.Join(dir, file.Name())
			data, err := os.ReadFile(fp)
			if err != nil {
				logger.Error("failed to read scenario file", "error", err, "fp", fp)
				continue // Skip this file
			}
			scenario := &models.RPScenario{}
			if err := json.Unmarshal(data, &scenario); err != nil {
				logger.Error("failed to unmarshal scenario file", "error", err, "fp", fp)
				continue // Skip this file
			}
			scenarios = append(scenarios, scenario)
		}
	}
	return scenarios, nil
}

func chooseParser(apiURL string) RespParser {
	if apiURL == cfg.RemoteAPI {
		return NewOpenRouterParser(logger)
	}
	return NewLCPRespParser(logger)
}

func init() {
	logger = slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{
		Level:     slog.LevelDebug,
		AddSource: true,
	}))
	cfg = config.LoadConfigOrDefault("config.toml")
}

func main() {
	mode := flag.String("mode", "questions", "Benchmark mode: 'questions' or 'rp'")
	flag.Parse()

	switch *mode {
	case "questions":
		questions, err := loadQuestions(cfg.QuestionsPath)
		if err != nil {
			panic(err)
		}
		answers, err := runBench(questions)
		if err != nil {
			panic(err)
		}
		data, err := json.MarshalIndent(answers, " ", " ")
		if err != nil {
			panic(err)
		}
		if err := os.WriteFile(filepath.Join(cfg.OutDir, "results.json"), data, 0666); err != nil {
			panic(err)
		}
	case "rp":
		scenarios, err := loadRPScenarios(cfg.RPScenariosDir)
		if err != nil {
			panic(err)
		}
		for _, scenario := range scenarios {
			logger.Info("running scenario", "name", scenario.Name)
			conversation, err := runRPBench(scenario)
			if err != nil {
				logger.Error("failed to run rp bench", "error", err, "scenario", scenario.Name)
				continue
			}
			if err := saveRPResult(scenario.Name, conversation); err != nil {
				logger.Error("failed to save rp result", "error", err, "scenario", scenario.Name)
			}
		}
	default:
		fmt.Println("Unknown mode, please use 'questions' or 'rp'")
	}
}

func saveRPResult(name string, conversation []models.RPMessage) error {
	date := time.Now().Format("2006-01-02")
	fn := fmt.Sprintf("%s_%s.txt", name, date)
	fp := filepath.Join(cfg.OutDir, fn)

	var b strings.Builder
	for _, msg := range conversation {
		b.WriteString(fmt.Sprintf("%s:\n%s\n\n", msg.Author, msg.Content))
	}

	return os.WriteFile(fp, []byte(b.String()), 0666)
}

func runRPBench(scenario *models.RPScenario) ([]models.RPMessage, error) {
	conversation := []models.RPMessage{}
	if scenario.FirstMsg != "" {
		conversation = append(conversation, models.RPMessage{Author: "Scenario", Content: scenario.FirstMsg})
	}

	for i := 0; i < cfg.MaxTurns; i++ {
		// User's turn (local model)
		userPrompt := buildRPPrompt(scenario.UserSysPrompt, conversation, scenario.UserName)
		userResp, err := callLLM(userPrompt, cfg.LocalAPI)
		if err != nil {
			return nil, fmt.Errorf("user turn failed: %w", err)
		}
		parser := chooseParser(cfg.LocalAPI)
		userText, err := parser.ParseBytes(userResp)
		if err != nil {
			return nil, fmt.Errorf("user turn failed parsing response: %w", err)
		}
		conversation = append(conversation, models.RPMessage{Author: scenario.UserName, Content: userText})

		// Character's turn (remote model)
		charPrompt := buildRPPrompt(scenario.CharSysPrompt, conversation, scenario.CharName)
		charResp, err := callLLM(charPrompt, cfg.RemoteAPI)
		if err != nil {
			return nil, fmt.Errorf("char turn failed: %w", err)
		}
		parser = chooseParser(cfg.RemoteAPI)
		charText, err := parser.ParseBytes(charResp)
		if err != nil {
			return nil, fmt.Errorf("char turn failed parsing response: %w", err)
		}
		conversation = append(conversation, models.RPMessage{Author: scenario.CharName, Content: charText})
	}
	return conversation, nil
}

func buildRPPrompt(sysPrompt string, history []models.RPMessage, characterName string) string {
	var b strings.Builder
	b.WriteString(sysPrompt)
	b.WriteString("\n\n")
	for _, msg := range history {
		b.WriteString(fmt.Sprintf("%s: %s\n", msg.Author, msg.Content))
	}
	b.WriteString(fmt.Sprintf("%s:", characterName))
	return b.String()
}

func processLLMResponse(respText string) (string, models.ToolCallInfo) {
	// Check if the response indicates tool usage
	var toolCall models.ToolCallInfo
	if strings.HasPrefix(respText, "[TOOL_CALL:") && strings.HasSuffix(respText, "]") {
		// Extract tool name from the marker
		toolName := strings.TrimPrefix(strings.TrimSuffix(respText, "]"), "[TOOL_CALL:")
		toolCall = models.ToolCallInfo{
			Name: toolName,
			// Arguments would need to be parsed from the actual response
		}
		// Remove the marker from the response text
		respText = fmt.Sprintf("Used tool: %s", toolName)
	}
	return respText, toolCall
}

func runBench(questions []models.Question) ([]models.Answer, error) {
	answers := []models.Answer{}
	for _, q := range questions {
		resp, err := callLLM(buildPrompt(q.Question), cfg.RemoteAPI) // Assuming remote for questions
		if err != nil {
			logger.Error("failed to call llm", "error", err)
			continue
		}
		parser := chooseParser(cfg.RemoteAPI)
		respText, err := parser.ParseBytes(resp)
		if err != nil {
			logger.Error("failed to parse llm response", "error", err)
			continue
		}
		
		// Process the response to detect tool usage
		respText, toolCall := processLLMResponse(respText)
		
		a := models.Answer{
			Q:        q,
			Answer:   respText,
			Model:    "default", // model name from resp?
			ToolCall: toolCall,
		}
		answers = append(answers, a)
	}
	return answers, nil
}

func buildPrompt(q string) string {
	return fmt.Sprintf(`Q:\n%s\nA:\nSure,`, q)
}

func callLLM(prompt string, apiURL string) ([]byte, error) {
	method := "POST"
	parser := chooseParser(apiURL)
	payloadReader := parser.MakePayload(prompt)

	var payloadBytes []byte
	if payloadReader != nil {
		var err error
		payloadBytes, err = io.ReadAll(payloadReader)
		if err != nil {
			return nil, fmt.Errorf("failed to read payload: %w", err)
		}
	}

	maxRetries := 6
	baseDelay := 2 * time.Second

	for attempt := 0; attempt < maxRetries; attempt++ {
		req, err := http.NewRequest(method, apiURL, bytes.NewReader(payloadBytes))
		if err != nil {
			return nil, fmt.Errorf("failed to create request: %w", err)
		}

		req.Header.Add("Content-Type", "application/json")
		req.Header.Add("Accept", "application/json")
		if apiURL == cfg.RemoteAPI {
			req.Header.Add("Authorization", "Bearer "+cfg.APIToken)
		}

		resp, err := httpClient.Do(req)
		if err != nil {
			if attempt == maxRetries-1 {
				return nil, fmt.Errorf("LLM call failed after %d retries on client.Do: %w", maxRetries, err)
			}
			logger.Error("http request failed; will retry", "error", err, "url", apiURL, "attempt", attempt)
			time.Sleep(baseDelay * time.Duration(1<<attempt))
			continue
		}

		body, err := io.ReadAll(resp.Body)
		resp.Body.Close()
		if err != nil {
			return nil, fmt.Errorf("failed to read response body: %w", err)
		}

		if resp.StatusCode >= 400 {
			if attempt == maxRetries-1 {
				return nil, fmt.Errorf("LLM call failed after %d retries, got status %d, body: %s", maxRetries, resp.StatusCode, string(body))
			}
			logger.Warn("retriable status code; will retry", "code", resp.StatusCode, "attempt", attempt, "body", string(body))
			time.Sleep(baseDelay * time.Duration(1<<attempt))
			continue
		}

		logger.Debug("llm resp", "body", string(body), "url", apiURL, "attempt", attempt)
		return body, nil
	}
	return nil, errors.New("exceeded max retries")
}