package common

import (
	"fmt"
	"strings"

	"one-api/types"

	"github.com/pkoukk/tiktoken-go"
)

var tokenEncoderMap = map[string]*tiktoken.Tiktoken{}
var defaultTokenEncoder *tiktoken.Tiktoken

func InitTokenEncoders() {
	SysLog("initializing token encoders")
	gpt35TokenEncoder, err := tiktoken.EncodingForModel("gpt-3.5-turbo")
	if err != nil {
		FatalLog(fmt.Sprintf("failed to get gpt-3.5-turbo token encoder: %s", err.Error()))
	}
	defaultTokenEncoder = gpt35TokenEncoder
	gpt4TokenEncoder, err := tiktoken.EncodingForModel("gpt-4")
	if err != nil {
		FatalLog(fmt.Sprintf("failed to get gpt-4 token encoder: %s", err.Error()))
	}
	for model, _ := range ModelRatio {
		if strings.HasPrefix(model, "gpt-3.5") {
			tokenEncoderMap[model] = gpt35TokenEncoder
		} else if strings.HasPrefix(model, "gpt-4") {
			tokenEncoderMap[model] = gpt4TokenEncoder
		} else {
			tokenEncoderMap[model] = nil
		}
	}
	SysLog("token encoders initialized")
}

func getTokenEncoder(model string) *tiktoken.Tiktoken {
	tokenEncoder, ok := tokenEncoderMap[model]
	if ok && tokenEncoder != nil {
		return tokenEncoder
	}
	if ok {
		tokenEncoder, err := tiktoken.EncodingForModel(model)
		if err != nil {
			SysError(fmt.Sprintf("failed to get token encoder for model %s: %s, using encoder for gpt-3.5-turbo", model, err.Error()))
			tokenEncoder = defaultTokenEncoder
		}
		tokenEncoderMap[model] = tokenEncoder
		return tokenEncoder
	}
	return defaultTokenEncoder
}

func getTokenNum(tokenEncoder *tiktoken.Tiktoken, text string) int {
	if ApproximateTokenEnabled {
		return int(float64(len(text)) * 0.38)
	}
	return len(tokenEncoder.Encode(text, nil, nil))
}

func CountTokenMessages(messages []types.ChatCompletionMessage, model string) int {
	tokenEncoder := getTokenEncoder(model)
	// Reference:
	// https://github.com/openai/openai-cookbook/blob/main/examples/How_to_count_tokens_with_tiktoken.ipynb
	// https://github.com/pkoukk/tiktoken-go/issues/6
	//
	// Every message follows <|start|>{role/name}\n{content}<|end|>\n
	var tokensPerMessage int
	var tokensPerName int
	if model == "gpt-3.5-turbo-0301" {
		tokensPerMessage = 4
		tokensPerName = -1 // If there's a name, the role is omitted
	} else {
		tokensPerMessage = 3
		tokensPerName = 1
	}
	tokenNum := 0
	for _, message := range messages {
		tokenNum += tokensPerMessage
		tokenNum += getTokenNum(tokenEncoder, message.StringContent())
		tokenNum += getTokenNum(tokenEncoder, message.Role)
		if message.Name != nil {
			tokenNum += tokensPerName
			tokenNum += getTokenNum(tokenEncoder, *message.Name)
		}
	}
	tokenNum += 3 // Every reply is primed with <|start|>assistant<|message|>
	return tokenNum
}

func CountTokenInput(input any, model string) int {
	switch input.(type) {
	case string:
		return CountTokenText(input.(string), model)
	case []string:
		text := ""
		for _, s := range input.([]string) {
			text += s
		}
		return CountTokenText(text, model)
	}
	return 0
}

func CountTokenText(text string, model string) int {
	tokenEncoder := getTokenEncoder(model)
	return getTokenNum(tokenEncoder, text)
}