// SiYuan - Build Your Eternal Digital Garden
// Copyright (c) 2020-present, b3log.org
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package util

import (
	"bytes"
	"context"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	gogpt "github.com/sashabaranov/go-gpt3"
	"github.com/siyuan-note/logging"
)

var (
	OpenAIAPIKey       = ""
	OpenAIAPITimeout   = 30 * time.Second
	OpenAIAPIProxy     = ""
	OpenAIAPIMaxTokens = 0
)

var cachedContextMsg []string

func ChatGPT(msg string) (ret string) {
	ret, retCtxMsgs := ChatGPTContinueWrite(msg, cachedContextMsg)
	cachedContextMsg = append(cachedContextMsg, retCtxMsgs...)
	return
}

func ChatGPTTranslate(msg string, lang string) (ret string) {
	msg = "Translate to " + lang + ":\n" + msg
	ret, _ = ChatGPTContinueWrite(msg, nil)
	return
}

func ChatGPTSummary(msg string, lang string) (ret string) {
	msg = "Summarized as follows, the result is in {" + lang + "}:\n" + msg
	ret, _ = ChatGPTContinueWrite(msg, nil)
	return
}

func ChatGPTContinueWrite(msg string, contextMsgs []string) (ret string, retContextMsgs []string) {
	if "" == OpenAIAPIKey {
		return
	}

	PushEndlessProgress("Requesting...")
	defer ClearPushProgress(100)

	c := newOpenAIClient()
	buf := &bytes.Buffer{}
	for i := 0; i < 7; i++ {
		part, stop := chatGPT(msg, contextMsgs, c)
		buf.WriteString(part)

		if stop {
			break
		}

		PushEndlessProgress("Continue requesting...")
	}

	ret = buf.String()
	ret = strings.TrimSpace(ret)
	retContextMsgs = append(retContextMsgs, msg, ret)
	return
}

func chatGPT(msg string, contextMsgs []string, c *gogpt.Client) (ret string, stop bool) {
	var reqMsgs []gogpt.ChatCompletionMessage
	if 7 < len(contextMsgs) {
		contextMsgs = contextMsgs[len(contextMsgs)-7:]
	}

	for _, ctxMsg := range contextMsgs {
		reqMsgs = append(reqMsgs, gogpt.ChatCompletionMessage{
			Role:    "user",
			Content: ctxMsg,
		})
	}
	reqMsgs = append(reqMsgs, gogpt.ChatCompletionMessage{
		Role:    "user",
		Content: msg,
	})

	req := gogpt.ChatCompletionRequest{
		Model:     gogpt.GPT3Dot5Turbo,
		MaxTokens: OpenAIAPIMaxTokens,
		Messages:  reqMsgs,
	}
	ctx, cancel := context.WithTimeout(context.Background(), OpenAIAPITimeout)
	defer cancel()
	resp, err := c.CreateChatCompletion(ctx, req)
	if nil != err {
		PushErrMsg("Requesting failed, please check kernel log for more details", 3000)
		logging.LogErrorf("create chat completion failed: %s", err)
		stop = true
		return
	}

	if 1 > len(resp.Choices) {
		stop = true
		return
	}

	buf := &strings.Builder{}
	choice := resp.Choices[0]
	buf.WriteString(choice.Message.Content)
	if "length" == choice.FinishReason {
		stop = false
	} else {
		stop = true
	}

	ret = buf.String()
	ret = strings.TrimSpace(ret)
	return
}

func newOpenAIClient() *gogpt.Client {
	config := gogpt.DefaultConfig(OpenAIAPIKey)
	if "" != OpenAIAPIProxy {
		proxyUrl, err := url.Parse(OpenAIAPIProxy)
		if nil != err {
			logging.LogErrorf("OpenAI API proxy failed: %v", err)
		} else {
			config.HTTPClient = &http.Client{Transport: &http.Transport{Proxy: http.ProxyURL(proxyUrl)}}
		}
	}
	return gogpt.NewClientWithConfig(config)
}

func initOpenAI() {
	OpenAIAPIKey = os.Getenv("SIYUAN_OPENAI_API_KEY")
	if "" == OpenAIAPIKey {
		return
	}

	timeout := os.Getenv("SIYUAN_OPENAI_API_TIMEOUT")
	if "" != timeout {
		timeoutInt, err := strconv.Atoi(timeout)
		if nil == err {
			OpenAIAPITimeout = time.Duration(timeoutInt) * time.Second
		}
	}

	proxy := os.Getenv("SIYUAN_OPENAI_API_PROXY")
	if "" != proxy {
		OpenAIAPIProxy = proxy
	}

	maxTokens := os.Getenv("SIYUAN_OPENAI_API_MAX_TOKENS")
	if "" != maxTokens {
		maxTokensInt, err := strconv.Atoi(maxTokens)
		if nil == err {
			OpenAIAPIMaxTokens = maxTokensInt
		}
	}

	logging.LogInfof("OpenAI API enabled [maxTokens=%d, timeout=%ds, proxy=%s]", OpenAIAPIMaxTokens, int(OpenAIAPITimeout.Seconds()), OpenAIAPIProxy)
}