package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"text/template"
	"time"

	"github.com/sirupsen/logrus"
)

// LLMClient abstracts LLM API calls
type LLMClient struct {
	APIKey  string
	BaseURL string
	Model   string
	Repo    ChatRepositoryAPI
}

// NewLLMClient constructs a new LLMClient with the given API key, base URL, model, and optional repository
func NewLLMClient(apiKey, baseURL string, model string, repo ChatRepositoryAPI) *LLMClient {
	return &LLMClient{APIKey: apiKey, BaseURL: baseURL, Model: model, Repo: repo}
}

func (llm *LLMClient) SetRepository(r ChatRepositoryAPI) { llm.Repo = r }

// helper to get correlation id from context
const correlationIDCtxKey = "corr_id"

func correlationIDFromCtx(ctx context.Context) string {
	v := ctx.Value(correlationIDCtxKey)
	if s, ok := v.(string); ok {
		return s
	}
	return ""
}

func (llm *LLMClient) persistRaw(ctx context.Context, phase, raw string) {
	if llm == nil || llm.Repo == nil || raw == "" {
		return
	}
	cid := correlationIDFromCtx(ctx)
	if cid == "" {
		return
	}
	_ = llm.Repo.SaveLLMRawEvent(ctx, cid, phase, raw)
}

// renderPrompt renders a Go template with the given data
func renderPrompt(tmplStr string, data any) (string, error) {
	tmpl, err := template.New("").Parse(tmplStr)
	if err != nil {
		return "", err
	}
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", err
	}
	return buf.String(), nil
}

// ExtractKeywords calls LLM to extract keywords from user message
func (llm *LLMClient) ExtractKeywords(ctx context.Context, message string) (map[string]interface{}, error) {
	_, parsed, err := llm.ExtractKeywordsRaw(ctx, message)
	return parsed, err
}

// ExtractKeywordsRaw returns the raw JSON string and parsed map
func (llm *LLMClient) ExtractKeywordsRaw(ctx context.Context, message string) (string, map[string]interface{}, error) {
	prompt, err := renderPrompt(appConfig.LLM.ExtractKeywordsPrompt, map[string]string{"Message": message})
	if err != nil {
		logrus.WithError(err).Error("[CONFIG] Failed to render ExtractKeywords prompt")
		return "", nil, err
	}
	logrus.WithField("prompt", prompt).Info("[LLM] ExtractKeywords prompt")
	format := map[string]interface{}{
		"type": "object",
		"properties": map[string]interface{}{
			"translate": map[string]interface{}{"type": "string"},
			"keyword":   map[string]interface{}{"type": "array", "items": map[string]interface{}{"type": "string"}},
			"animal":    map[string]interface{}{"type": "string"},
		},
		"required": []string{"translate", "keyword", "animal"},
	}
	resp, err := llm.openAICompletion(ctx, prompt, format)
	logrus.WithFields(logrus.Fields{"response": resp, "err": err}).Info("[LLM] ExtractKeywords response")
	if err != nil {
		return resp, nil, err // return whatever raw we got (may be empty)
	}
	var result map[string]interface{}
	if err := json.Unmarshal([]byte(resp), &result); err != nil {
		return resp, nil, err
	}
	llm.persistRaw(ctx, "extract_keywords", resp)
	return resp, result, nil
}

// DisambiguateBestMatch calls LLM to pick best match from candidates
func (llm *LLMClient) DisambiguateBestMatch(ctx context.Context, message string, candidates []Visit) (string, error) {
	_, vr, err := llm.DisambiguateBestMatchRaw(ctx, message, candidates)
	return vr, err
}

// DisambiguateBestMatchRaw returns raw JSON and visitReason
func (llm *LLMClient) DisambiguateBestMatchRaw(ctx context.Context, message string, candidates []Visit) (string, string, error) {
	format := map[string]interface{}{
		"type": "object",
		"properties": map[string]interface{}{
			"visitReason": map[string]interface{}{"type": "string"},
		},
		"required": []string{"visitReason"},
	}
	entries, _ := json.Marshal(candidates)
	prompt, err := renderPrompt(appConfig.LLM.DisambiguatePrompt, map[string]string{"Entries": string(entries), "Message": message})
	if err != nil {
		logrus.WithError(err).Error("[CONFIG] Failed to render Disambiguate prompt")
		return "", "", err
	}
	logrus.WithField("prompt", prompt).Info("[LLM] DisambiguateBestMatch prompt")
	resp, err := llm.openAICompletion(ctx, prompt, format)
	logrus.WithFields(logrus.Fields{"response": resp, "err": err}).Info("[LLM] DisambiguateBestMatch response")
	if err != nil {
		return resp, "", err
	}
	var parsed map[string]string
	if err := json.Unmarshal([]byte(resp), &parsed); err != nil {
		return resp, "", fmt.Errorf("failed to unmarshal disambiguation response: %w", err)
	}
	visitReason := strings.TrimSpace(parsed["visitReason"])
	if visitReason == "" {
		return resp, "", fmt.Errorf("visitReason not found in response")
	}
	llm.persistRaw(ctx, "disambiguate", resp)
	return resp, visitReason, nil
}

// openAICompletion now supports both Ollama (default local) and OpenRouter/OpenAI-compatible APIs without external branching.
// It auto-detects by inspecting the BaseURL. If the URL contains "openrouter.ai" or "/v1/", it assumes OpenAI-style.
func (llm *LLMClient) openAICompletion(ctx context.Context, prompt string, format map[string]interface{}) (string, error) {
	apiURL := llm.BaseURL
	if apiURL == "" {
		// Default to Ollama local chat endpoint
		apiURL = "http://localhost:11434/api/chat"
	}

	isOpenAIStyle := strings.Contains(apiURL, "openrouter.ai") || strings.Contains(apiURL, "/v1/")

	// Helper to stringify the expected JSON schema for instructions
	schemaDesc := func() string {
		b, _ := json.MarshalIndent(format, "", "  ")
		return string(b)
	}

	truncate := func(s string, n int) string {
		if len(s) <= n {
			return s
		}
		return s[:n] + "...<truncated>"
	}

	buildBody := func() map[string]interface{} {
		if isOpenAIStyle {
			return map[string]interface{}{
				"model": llm.Model,
				"messages": []map[string]string{
					{"role": "system", "content": "You are a strict JSON generator. ONLY output valid JSON matching this schema: " + schemaDesc() + " Do not add explanations."},
					{"role": "user", "content": prompt},
				},
				"response_format": map[string]interface{}{"type": "json_object"},
			}
		}
		// Ollama style
		return map[string]interface{}{
			"model":    llm.Model,
			"messages": []map[string]string{{"role": "user", "content": prompt}},
			"stream":   false,
			"format":   format,
		}
	}

	body := buildBody()

	doRequest := func(body map[string]interface{}) (raw []byte, status int, err error, dur time.Duration) {
		jsonBody, _ := json.Marshal(body)
		bodySize := len(jsonBody)
		logrus.WithFields(logrus.Fields{
			"event":           "llm_request",
			"api_url":         apiURL,
			"model":           llm.Model,
			"is_openai_style": isOpenAIStyle,
			"prompt_len":      len(prompt),
			"body_size":       bodySize,
		}).Info("[LLM] sending request")
		req, _ := http.NewRequestWithContext(ctx, http.MethodPost, apiURL, bytes.NewBuffer(jsonBody))
		if llm.APIKey != "" {
			req.Header.Set("Authorization", "Bearer "+llm.APIKey)
		}
		req.Header.Set("Content-Type", "application/json")
		req.Header.Set("Accept", "application/json")
		if strings.Contains(apiURL, "openrouter.ai") {
			req.Header.Set("Referer", "https://github.com/")
			req.Header.Set("X-Title", "vetrag-app")
		}
		start := time.Now()
		client := &http.Client{}
		resp, err := client.Do(req)
		if err != nil {
			return nil, 0, err, time.Since(start)
		}
		defer resp.Body.Close()
		raw, rerr := io.ReadAll(resp.Body)
		return raw, resp.StatusCode, rerr, time.Since(start)
	}

	raw, status, err, dur := doRequest(body)
	if err != nil {
		logrus.WithFields(logrus.Fields{
			"event":      "llm_response",
			"status":     status,
			"latency_ms": dur.Milliseconds(),
			"error":      err,
		}).Error("[LLM] request failed")
		return "", err
	}
	logrus.WithFields(logrus.Fields{
		"event":      "llm_raw_response",
		"status":     status,
		"latency_ms": dur.Milliseconds(),
		"raw_trunc":  truncate(string(raw), 600),
		"raw_len":    len(raw),
	}).Debug("[LLM] raw response body")

	parseVariant := "unknown"

	// Attempt Ollama format parse
	var ollama struct {
		Message struct {
			Content string `json:"content"`
		} `json:"message"`
		Error string `json:"error"`
	}
	if err := json.Unmarshal(raw, &ollama); err == nil && ollama.Message.Content != "" {
		parseVariant = "ollama"
		content := ollama.Message.Content
		logrus.WithFields(logrus.Fields{
			"event":         "llm_response",
			"status":        status,
			"latency_ms":    dur.Milliseconds(),
			"parse_variant": parseVariant,
			"content_len":   len(content),
			"content_snip":  truncate(content, 300),
		}).Info("[LLM] parsed response")
		return content, nil
	}

	// Attempt OpenAI/OpenRouter style parse
	var openAI struct {
		Choices []struct {
			Message struct {
				Content string `json:"content"`
			} `json:"message"`
		} `json:"choices"`
		Error *struct {
			Message string `json:"message"`
			Type    string `json:"type"`
		} `json:"error"`
	}
	if err := json.Unmarshal(raw, &openAI); err == nil {
		if openAI.Error != nil || status >= 400 {
			parseVariant = "openai"
			var msg string
			if openAI.Error != nil {
				msg = openAI.Error.Message
			} else {
				msg = string(raw)
			}
			logrus.WithFields(logrus.Fields{
				"event":         "llm_response",
				"status":        status,
				"latency_ms":    dur.Milliseconds(),
				"parse_variant": parseVariant,
				"error":         msg,
			}).Error("[LLM] provider error")
			return "", fmt.Errorf("provider error: %s", msg)
		}
		if len(openAI.Choices) > 0 && openAI.Choices[0].Message.Content != "" {
			parseVariant = "openai"
			content := openAI.Choices[0].Message.Content
			logrus.WithFields(logrus.Fields{
				"event":         "llm_response",
				"status":        status,
				"latency_ms":    dur.Milliseconds(),
				"parse_variant": parseVariant,
				"content_len":   len(content),
				"content_snip":  truncate(content, 300),
			}).Info("[LLM] parsed response")
			return content, nil
		}
	}

	logrus.WithFields(logrus.Fields{
		"event":         "llm_response",
		"status":        status,
		"latency_ms":    dur.Milliseconds(),
		"parse_variant": parseVariant,
		"raw_snip":      truncate(string(raw), 300),
	}).Error("[LLM] unrecognized response format")

	return "", fmt.Errorf("unrecognized LLM response format: %.200s", string(raw))
}

// LLMClientAPI allows mocking LLMClient in other places
// Only public methods should be included

type LLMClientAPI interface {
	ExtractKeywords(ctx context.Context, message string) (map[string]interface{}, error)
	DisambiguateBestMatch(ctx context.Context, message string, candidates []Visit) (string, error)
}

var _ LLMClientAPI = (*LLMClient)(nil)