package main

import (
	"bytes"
	"context"
	"fmt"
	"html/template"
	"io/ioutil"
	"net/http"
	"os"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/sirupsen/logrus"
	"gopkg.in/yaml.v3"
)

// Procedure represents a single procedure for a visit reason
type Procedure struct {
	Name        string `yaml:"name" json:"name"`
	Price       int    `yaml:"price" json:"price"`
	DurationMin int    `yaml:"duration_minutes" json:"duration_minutes"`
}

// Reason represents a visit reason entry
type Reason struct {
	ID         string      `yaml:"id" json:"id"`
	Reason     string      `yaml:"reason" json:"reason"`
	Keywords   []string    `yaml:"keywords" json:"keywords"`
	Procedures []Procedure `yaml:"procedures" json:"procedures"`
	Notes      string      `yaml:"notes" json:"notes,omitempty"`
}

var reasonsDB []Reason

func loadYAMLDB(path string) error {
	data, err := ioutil.ReadFile(path)
	if err != nil {
		return err
	}
	return yaml.Unmarshal(data, &reasonsDB)
}

// ChatRequest represents the incoming chat message
type ChatRequest struct {
	Message string `json:"message"`
}

// ChatResponse represents the response to the frontend
type ChatResponse struct {
	Match         *string     `json:"match"`
	Procedures    []Procedure `json:"procedures,omitempty"`
	TotalPrice    int         `json:"total_price,omitempty"`
	TotalDuration int         `json:"total_duration,omitempty"`
	Notes         string      `json:"notes,omitempty"`
}

// Config holds all prompts and settings
type Config struct {
	LLM struct {
		ExtractKeywordsPrompt string `yaml:"extract_keywords_prompt"`
		DisambiguatePrompt    string `yaml:"disambiguate_prompt"`
	} `yaml:"llm"`
}

var appConfig Config

func loadConfig(path string) error {
	data, err := ioutil.ReadFile(path)
	if err != nil {
		return err
	}
	return yaml.Unmarshal(data, &appConfig)
}

// naiveKeywordExtract splits message into lowercase words (placeholder for LLM)
func naiveKeywordExtract(msg string) []string {
	// TODO: Replace with LLM call
	words := make(map[string]struct{})
	for _, w := range strings.FieldsFunc(strings.ToLower(msg), func(r rune) bool {
		return r < 'a' || r > 'z' && r < 'á' || r > 'ű'
	}) {
		words[w] = struct{}{}
	}
	res := make([]string, 0, len(words))
	for w := range words {
		res = append(res, w)
	}
	return res
}

// findCandidates returns reasons with overlapping keywords
func findCandidates(keywords []string) []Reason {
	kwSet := make(map[string]struct{})
	for _, k := range keywords {
		kwSet[k] = struct{}{}
	}
	var candidates []Reason
	for _, r := range reasonsDB {
		for _, k := range r.Keywords {
			if _, ok := kwSet[strings.ToLower(k)]; ok {
				candidates = append(candidates, r)
				break
			}
		}
	}
	return candidates
}

// sumProcedures calculates total price and duration
func sumProcedures(procs []Procedure) (int, int) {
	totalPrice := 0
	totalDuration := 0
	for _, p := range procs {
		totalPrice += p.Price
		totalDuration += p.DurationMin
	}
	return totalPrice, totalDuration
}

// 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
}

var uiTemplate *template.Template

func loadUITemplate(path string) error {
	tmpl, err := template.ParseFiles(path)
	if err != nil {
		return err
	}
	uiTemplate = tmpl
	return nil
}

func main() {
	logrus.SetFormatter(&logrus.TextFormatter{FullTimestamp: true})
	logrus.SetLevel(logrus.InfoLevel)

	if err := loadConfig("config.yaml"); err != nil {
		logrus.Fatalf("Failed to load config.yaml: %v", err)
	}
	logrus.Infof("Loaded config: %+v", appConfig)
	if err := loadYAMLDB("db.yaml"); err != nil {
		logrus.Fatalf("Failed to load db.yaml: %v", err)
	}
	fmt.Printf("Loaded %d reasons from db.yaml\n", len(reasonsDB))
	if err := loadUITemplate("ui.html"); err != nil {
		logrus.Fatalf("Failed to load ui.html: %v", err)
	}
	llm := &LLMClient{
		APIKey:  os.Getenv("OPENAI_API_KEY"),
		BaseURL: os.Getenv("OPENAI_BASE_URL"),
	}
	r := gin.Default()
	r.GET("/", func(c *gin.Context) {
		c.Status(200)
		uiTemplate.Execute(c.Writer, nil)
	})
	r.POST("/chat", func(c *gin.Context) {
		var req ChatRequest
		if err := c.ShouldBindJSON(&req); err != nil {
			logrus.WithError(err).Error("Invalid request")
			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request"})
			return
		}
		ctx := context.Background()
		keywords, err := llm.ExtractKeywords(ctx, req.Message)
		candidates := findCandidates(keywords)
		bestID := ""
		if len(candidates) > 0 && err == nil {
			bestID, err = llm.DisambiguateBestMatch(ctx, req.Message, candidates)
		}
		logRequest(req, keywords, candidates, bestID, err)
		if err != nil || len(keywords) == 0 || len(candidates) == 0 || bestID == "" {
			c.JSON(http.StatusOK, ChatResponse{Match: nil})
			return
		}
		var best *Reason
		for i := range candidates {
			if candidates[i].ID == bestID {
				best = &candidates[i]
				break
			}
		}
		if best == nil {
			c.JSON(http.StatusOK, ChatResponse{Match: nil})
			return
		}
		totalPrice, totalDuration := sumProcedures(best.Procedures)
		logrus.WithFields(logrus.Fields{
			"match":          best.ID,
			"total_price":    totalPrice,
			"total_duration": totalDuration,
			"notes":          best.Notes,
		}).Info("Responding with match")
		c.JSON(http.StatusOK, ChatResponse{
			Match:         &best.ID,
			Procedures:    best.Procedures,
			TotalPrice:    totalPrice,
			TotalDuration: totalDuration,
			Notes:         best.Notes,
		})
	})

	r.Run(":8080")
}

// logRequest logs incoming chat requests and extracted info
func logRequest(req ChatRequest, keywords []string, candidates []Reason, bestID string, err error) {
	logrus.WithFields(logrus.Fields{
		"message":    req.Message,
		"keywords":   keywords,
		"candidates": getCandidateIDs(candidates),
		"bestID":     bestID,
		"err":        err,
	}).Info("Chat request trace")
}

func getCandidateIDs(candidates []Reason) []string {
	ids := make([]string, len(candidates))
	for i, c := range candidates {
		ids[i] = c.ID
	}
	return ids
}