package service

import (
	"github.com/Wei-Shaw/sub2api/internal/config"
	"github.com/Wei-Shaw/sub2api/internal/pkg/openai"
	"github.com/gin-gonic/gin"
)

const (
	// CodexClientRestrictionReasonDisabled 表示账号未开启 codex_cli_only。
	CodexClientRestrictionReasonDisabled = "codex_cli_only_disabled"
	// CodexClientRestrictionReasonMatchedUA 表示请求命中官方客户端 UA 白名单。
	CodexClientRestrictionReasonMatchedUA = "official_client_user_agent_matched"
	// CodexClientRestrictionReasonMatchedOriginator 表示请求命中官方客户端 originator 白名单。
	CodexClientRestrictionReasonMatchedOriginator = "official_client_originator_matched"
	// CodexClientRestrictionReasonNotMatchedUA 表示请求未命中官方客户端 UA 白名单。
	CodexClientRestrictionReasonNotMatchedUA = "official_client_user_agent_not_matched"
	// CodexClientRestrictionReasonForceCodexCLI 表示通过 ForceCodexCLI 配置兜底放行。
	CodexClientRestrictionReasonForceCodexCLI = "force_codex_cli_enabled"
)

// CodexClientRestrictionDetectionResult 是 codex_cli_only 统一检测入口结果。
type CodexClientRestrictionDetectionResult struct {
	Enabled bool
	Matched bool
	Reason  string
}

// CodexClientRestrictionDetector 定义 codex_cli_only 统一检测入口。
type CodexClientRestrictionDetector interface {
	Detect(c *gin.Context, account *Account) CodexClientRestrictionDetectionResult
}

// OpenAICodexClientRestrictionDetector 为 OpenAI OAuth codex_cli_only 的默认实现。
type OpenAICodexClientRestrictionDetector struct {
	cfg *config.Config
}

func NewOpenAICodexClientRestrictionDetector(cfg *config.Config) *OpenAICodexClientRestrictionDetector {
	return &OpenAICodexClientRestrictionDetector{cfg: cfg}
}

func (d *OpenAICodexClientRestrictionDetector) Detect(c *gin.Context, account *Account) CodexClientRestrictionDetectionResult {
	if account == nil || !account.IsCodexCLIOnlyEnabled() {
		return CodexClientRestrictionDetectionResult{
			Enabled: false,
			Matched: false,
			Reason:  CodexClientRestrictionReasonDisabled,
		}
	}

	if d != nil && d.cfg != nil && d.cfg.Gateway.ForceCodexCLI {
		return CodexClientRestrictionDetectionResult{
			Enabled: true,
			Matched: true,
			Reason:  CodexClientRestrictionReasonForceCodexCLI,
		}
	}

	userAgent := ""
	originator := ""
	if c != nil {
		userAgent = c.GetHeader("User-Agent")
		originator = c.GetHeader("originator")
	}
	if openai.IsCodexOfficialClientRequest(userAgent) {
		return CodexClientRestrictionDetectionResult{
			Enabled: true,
			Matched: true,
			Reason:  CodexClientRestrictionReasonMatchedUA,
		}
	}
	if openai.IsCodexOfficialClientOriginator(originator) {
		return CodexClientRestrictionDetectionResult{
			Enabled: true,
			Matched: true,
			Reason:  CodexClientRestrictionReasonMatchedOriginator,
		}
	}

	return CodexClientRestrictionDetectionResult{
		Enabled: true,
		Matched: false,
		Reason:  CodexClientRestrictionReasonNotMatchedUA,
	}
}