package main

import (
	"bytes"
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"

	"github.com/joho/godotenv"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"github.com/tmc/langchaingo/llms"
	"github.com/tmc/langchaingo/llms/ollama"
)

type CodeBlockParser struct {
	processed  int
	foundStart bool
	foundEnd   bool
}

func NewCodeBlockParser() *CodeBlockParser {
	return &CodeBlockParser{
		processed:  0,
		foundStart: false,
		foundEnd:   false,
	}
}

func (p *CodeBlockParser) ParseStream(chunk []byte) []byte {
	if !p.foundStart {
		if bytes.Contains(chunk, []byte("```")) {
			p.foundStart = true
			chunk = nil
		}
	}

	if p.foundStart && p.processed == 1 {
		chunk = nil
	}

	if p.foundStart && !p.foundEnd {
		if bytes.Contains(chunk, []byte("```")) {
			p.foundEnd = true
			chunk = nil
		}
	}

	p.processed += 1
	return chunk
}

func main() {
	err := godotenv.Load()

	if err != nil {
		log.Fatal("Error loading environment!")
	}

	LLM_MODEL := os.Getenv("LLM_MODEL")
	PORT := os.Getenv("PORT")

	if len(LLM_MODEL) == 0 {
		log.Fatal("No LLM model specified in environment!")
	}

	if len(PORT) == 0 {
		PORT = "8080"
	}

	ech := echo.New()

	ech.Use(middleware.CORS())
	ech.GET("/generate", func(ctx echo.Context) error {
		lines, err := strconv.Atoi(ctx.QueryParam("lines"))

		if err != nil {
			return ctx.String(http.StatusBadRequest, "Lines param is not provided or incorrect!")
		}

		lang := ctx.QueryParam("lang")

		if lang == "" {
			return ctx.String(http.StatusBadRequest, "Lang param is not provided or incorrect!")
		}

		ctx.Response().Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSON)
		ctx.Response().WriteHeader(http.StatusOK)

		llm, err := ollama.New(ollama.WithModel(fmt.Sprintf("%s", LLM_MODEL)))

		if err != nil {
			log.Fatal(err)
		}

		parser := NewCodeBlockParser()
		ollamaCtx := context.Background()
		prompt := []llms.MessageContent{
			llms.TextParts(llms.ChatMessageTypeSystem, `You must only generate code without any descriptions. Also don't include any code comments and use spaces instead of tabs for spacing. Most importantly. Most importantly you must remove any markdown code fences that wrap the content!`),
			llms.TextParts(llms.ChatMessageTypeHuman, fmt.Sprintf(`
				Generate a maximum of %d lines of code from a well known open source project in the %s programming language.`, lines, lang)),
		}

		if _, err := llm.GenerateContent(ollamaCtx, prompt, llms.WithStreamingFunc(func(streamCtx context.Context, chunk []byte) error {
			cleaned := parser.ParseStream(chunk)

			if len(cleaned) > 0 {
				ctx.Response().Write(cleaned)
				ctx.Response().Flush()
			}

			return nil
		})); err != nil {
			log.Fatal(err)
			return ctx.String(http.StatusInternalServerError, err.Error())
		}

		return nil
	})

	ech.Logger.Fatal(ech.Start(fmt.Sprintf(":%s", PORT)))
}