package mcp

import (
	"context"
	"strings"
	"time"

	"github.com/google/uuid"

	"github.com/yan1h/agent-coding-workflow/internal/audit"
	"github.com/yan1h/agent-coding-workflow/internal/infra/errs"
)

// TokenService 是 MCP token 的业务编排层。三类入口：
//   - IssueAdmin：admin 后台手动签发，必须给 expires_at
//   - IssueSystemToken：ACP supervisor 起 session 时调，绑定 acp_session_id
//   - Authenticate：HTTP 中间件调，验 plaintext + 返回 user_id + scope
//
// 撤销与列表通过 Repository 直接调即可，不在 service 上加薄壳。
type TokenService interface {
	IssueAdmin(ctx context.Context, in IssueAdminInput) (IssueResult, error)
	IssueSystemToken(ctx context.Context, in IssueSystemTokenInput) (IssueResult, error)
	Authenticate(ctx context.Context, plaintext string) (*MCPToken, error)
	Revoke(ctx context.Context, id, byUserID uuid.UUID) error
	RevokeBySession(ctx context.Context, sessionID uuid.UUID) error
}

// IssueAdminInput 是 admin 签发时的入参。UserID 缺省 = 当前 admin 自己（由调用方填）。
// Name 必填；ExpiresAt 必填（spec §10 决策 #14：防长期泄露）。
type IssueAdminInput struct {
	UserID    uuid.UUID
	Name      string
	Scope     Scope
	ExpiresAt time.Time
	CreatedBy uuid.UUID // 当前 admin 用户 ID
}

// IssueSystemTokenInput 是 ACP session 启动时的入参。
type IssueSystemTokenInput struct {
	UserID       uuid.UUID
	ACPSessionID uuid.UUID
	ProjectIDs   []uuid.UUID
	Tools        []string      // 缺省 nil = 系统默认（不含 chat）
	ExpiresIn    time.Duration // 默认 24h
}

// IssueResult 是签发返回。Plaintext 仅此一次返回；调用方须立即转交给客户端。
type IssueResult struct {
	ID        uuid.UUID
	Plaintext string
	ExpiresAt *time.Time
}

// defaultSystemTools 是 system token 的默认工具白名单（spec §6.2）。
// 不含 list_recent_messages：agent 不该看用户私人对话历史。
var defaultSystemTools = []string{
	"list_projects", "list_workspaces", "list_requirements", "list_issues",
	"get_issue", "get_requirement",
	"create_issue", "update_issue", "close_issue", "reopen_issue", "assign_issue",
	"create_requirement", "update_requirement", "close_requirement", "reopen_requirement", "set_requirement_phase",
}

// NewTokenService 构造 service。
func NewTokenService(repo Repository, audit audit.Recorder) TokenService {
	return &tokenService{repo: repo, audit: audit}
}

type tokenService struct {
	repo  Repository
	audit audit.Recorder
}

// IssueAdmin 签发一个长期 admin token。Name + ExpiresAt 必填；scope 可空（= 全权）。
// 写一条 audit `mcp.token.create`。
func (s *tokenService) IssueAdmin(ctx context.Context, in IssueAdminInput) (IssueResult, error) {
	if strings.TrimSpace(in.Name) == "" {
		return IssueResult{}, errs.New(errs.CodeMcpTokenNameRequired, "name is required")
	}
	if in.ExpiresAt.IsZero() {
		return IssueResult{}, errs.New(errs.CodeMcpTokenExpiresRequired, "expires_at is required for admin token")
	}

	plain, hash, err := NewToken()
	if err != nil {
		return IssueResult{}, errs.Wrap(err, errs.CodeInternal, "generate token plaintext")
	}

	id := uuid.New()
	created, err := s.repo.Create(ctx, &MCPToken{
		ID:        id,
		TokenHash: hash,
		UserID:    in.UserID,
		Name:      in.Name,
		Issuer:    IssuerAdmin,
		Scope:     in.Scope,
		ExpiresAt: &in.ExpiresAt,
		CreatedBy: in.CreatedBy,
	})
	if err != nil {
		return IssueResult{}, err
	}

	_ = s.audit.Record(ctx, audit.Entry{
		UserID:     &in.CreatedBy,
		Action:     "mcp.token.create",
		TargetType: "mcp_token",
		TargetID:   created.ID.String(),
		Metadata: map[string]any{
			"token_id":   created.ID.String(),
			"user_id":    in.UserID.String(),
			"name":       in.Name,
			"scope":      in.Scope,
			"expires_at": in.ExpiresAt,
		},
	})

	return IssueResult{
		ID:        created.ID,
		Plaintext: plain,
		ExpiresAt: created.ExpiresAt,
	}, nil
}

func (s *tokenService) IssueSystemToken(ctx context.Context, in IssueSystemTokenInput) (IssueResult, error) {
	panic("not implemented: IssueSystemToken")
}
func (s *tokenService) Authenticate(ctx context.Context, plaintext string) (*MCPToken, error) {
	panic("not implemented: Authenticate")
}
func (s *tokenService) Revoke(ctx context.Context, id, byUserID uuid.UUID) error {
	panic("not implemented: Revoke")
}
func (s *tokenService) RevokeBySession(ctx context.Context, sessionID uuid.UUID) error {
	panic("not implemented: RevokeBySession")
}