package openai

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"time"

	"github.com/go-skynet/LocalAI/core/backend"
	"github.com/go-skynet/LocalAI/core/services"
	"github.com/go-skynet/LocalAI/pkg/model"
	"github.com/go-skynet/LocalAI/pkg/schema"
	"github.com/gofiber/fiber/v2"
	"github.com/google/uuid"
	"github.com/rs/zerolog/log"
	"github.com/valyala/fasthttp"
)

// https://platform.openai.com/docs/api-reference/completions
func CompletionEndpoint(cl *services.ConfigLoader, ml *model.ModelLoader, so *schema.StartupOptions) func(c *fiber.Ctx) error {
	id := uuid.New().String()
	created := int(time.Now().Unix())

	return func(c *fiber.Ctx) error {
		modelName, input, err := readInput(c, so, ml, true)
		if err != nil {
			return fmt.Errorf("failed reading parameters from request:%w", err)
		}

		log.Debug().Msgf("`input`: %+v", input)

		if input.Stream {
			log.Debug().Msgf("Stream request received")
			c.Context().SetContentType("text/event-stream")
			//c.Response().Header.SetContentType(fiber.MIMETextHTMLCharsetUTF8)
			//c.Set("Content-Type", "text/event-stream")
			c.Set("Cache-Control", "no-cache")
			c.Set("Connection", "keep-alive")
			c.Set("Transfer-Encoding", "chunked")

			responses, err := backend.StreamingCompletionGenerationOpenAIRequest(modelName, input, cl, ml, so)
			if err != nil {
				return fmt.Errorf("failed establishing streaming completion request :%w", err)
			}
			c.Context().SetBodyStreamWriter(fasthttp.StreamWriter(func(w *bufio.Writer) {

				for ev := range responses {
					var buf bytes.Buffer
					enc := json.NewEncoder(&buf)
					enc.Encode(ev)

					log.Debug().Msgf("Sending chunk: %s", buf.String())
					fmt.Fprintf(w, "data: %v\n", buf.String())
					w.Flush()
				}

				resp := &schema.OpenAIResponse{
					ID:      id,
					Created: created,
					Model:   input.Model, // we have to return what the user sent here, due to OpenAI spec.
					Choices: []schema.Choice{
						{
							Index:        0,
							FinishReason: "stop",
						},
					},
					Object: "text_completion",
				}
				respData, _ := json.Marshal(resp)

				w.WriteString(fmt.Sprintf("data: %s\n\n", respData))
				w.WriteString("data: [DONE]\n\n")
				w.Flush()
			}))
			return nil
		}

		///////////

		resp, err := backend.CompletionGenerationOpenAIRequest(modelName, input, cl, ml, so)
		if err != nil {
			return fmt.Errorf("error generating completion request: +%w", err)
		}
		jsonResult, _ := json.Marshal(resp)
		log.Debug().Msgf("Response: %s", jsonResult)

		// Return the prediction in the response body
		return c.JSON(resp)
	}
}