// Copyright 2022 E99p1ant. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package censor

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
)

type ForbiddenType string

const (
	ForbiddenTypeSpam        ForbiddenType = "spam"
	ForbiddenTypeAd          ForbiddenType = "ad"
	ForbiddenTypePolitics    ForbiddenType = "politics"
	ForbiddenTypeTerrorism   ForbiddenType = "terrorism"
	ForbiddenTypeAbuse       ForbiddenType = "abuse"
	ForbiddenTypePorn        ForbiddenType = "porn"
	ForbiddenTypeFlood       ForbiddenType = "flood"
	ForbiddenTypeContraband  ForbiddenType = "contraband"
	ForbiddenTypeMeaningless ForbiddenType = "meaningless"
	ForbiddenTypeHarmful     ForbiddenType = "harmful"
)

func (f ForbiddenType) String() string {
	return map[ForbiddenType]string{
		ForbiddenTypeSpam:        "含垃圾信息",
		ForbiddenTypeAd:          "广告",
		ForbiddenTypePolitics:    "涉政",
		ForbiddenTypeTerrorism:   "暴恐",
		ForbiddenTypeAbuse:       "辱骂",
		ForbiddenTypePorn:        "色情",
		ForbiddenTypeFlood:       "灌水",
		ForbiddenTypeContraband:  "违禁",
		ForbiddenTypeMeaningless: "无意义",
		ForbiddenTypeHarmful:     "不良场景",
	}[f]
}

type TextCensorResponse struct {
	SourceName    string          `json:"source_name"`
	Pass          bool            `json:"pass"`
	ForbiddenType ForbiddenType   `json:"forbidden_type"`
	Hint          string          `json:"hint"`
	Confidence    float64         `json:"confidence"`
	RawResponse   json.RawMessage `json:"raw_response"`
}

func (r *TextCensorResponse) ToJSON() []byte {
	jsonBytes, _ := json.Marshal(r)
	return jsonBytes
}

func (r *TextCensorResponse) ErrorMessage() string {
	errorMessage := "内容安全检查不通过"
	if r.ForbiddenType != "" {
		errorMessage += fmt.Sprintf(" [%s]", r.ForbiddenType.String())
	}
	if r.Hint != "" {
		errorMessage += fmt.Sprintf("，相关标签：%q", r.Hint)
	}
	return errorMessage
}

type TextCensor interface {
	Censor(ctx context.Context, text string) (*TextCensorResponse, error)
	String() string
}

var TrustedHosts = []string{
	"xhslink.com", // 小红书
	"weibo.com",   // 微博
	"b23.tv",      // Bilibili
	"acfun.cn",
	"aixifan.com",
	"github.com",
	// 自有域名：旧域 tama.guru 保留至 2026-12 到期前的过渡期结束，
	// 期间用户分享的旧链接仍需视为可信（不被判为广告）；新域 shiroko.one 为主域。
	"tama.guru",
	"shiroko.one",
	"337845818.best",
	"x.com",
	"bilibili.com",
}

// RemoveTrustedURL removes the trusted URL from the text,
// in order to bypass the URL censoring.
// 仅当可信域名后紧跟路径分隔符（/ ? #）或位于字符串结尾时才视为可信，
// 避免 github.com.evil.tld 被朴素替换误判为 github.com 之子域而漏审。
func RemoveTrustedURL(str string) string {
	for _, host := range TrustedHosts {
		for _, protocol := range []string{"http://", "https://"} {
			needle := protocol + host
			var b strings.Builder
			rest := str
			for {
				idx := strings.Index(rest, needle)
				if idx < 0 {
					b.WriteString(rest)
					break
				}
				b.WriteString(rest[:idx])
				after := rest[idx+len(needle):]
				if len(after) == 0 || after[0] == '/' || after[0] == '?' || after[0] == '#' {
					// 可信域名边界：跳过该前缀，从域名之后继续（域名本身被移除，不进入审核）。
					rest = after
				} else {
					// 非可信域名边界（如 github.com.evil）：保留前缀，从其后继续扫描。
					b.WriteString(needle)
					rest = after
				}
			}
			str = b.String()
		}
	}
	return str
}