package docgov

import (
	"errors"
	"time"
)

var (
	ErrDocumentNotFound         = errors.New("docgov: document not found")
	ErrDocumentLocked           = errors.New("docgov: document is locked, direct modification prohibited")
	ErrOnlyAuthorCanEdit        = errors.New("docgov: only the designated author is allowed to edit or modify document content")
	ErrReviewerCannotEdit       = errors.New("docgov: reviewers are not allowed to edit document content, only comments and review decisions are permitted")
	ErrApproverCannotEdit       = errors.New("docgov: approvers are not allowed to edit document content, only comments and approval decisions are permitted")
	ErrInvalidStateTransition   = errors.New("docgov: invalid document lifecycle state transition")
	ErrRejectReasonRequired     = errors.New("docgov: rejection reason must not be empty")
	ErrUnauthorizedActor        = errors.New("docgov: actor is not authorized for this role or action")
	ErrProposalNotFound         = errors.New("docgov: change proposal not found")
	ErrProposalAlreadyDecided   = errors.New("docgov: change proposal has already been decided")
	ErrChangeProposalPending    = errors.New("docgov: document is claimed and has pending change proposal waiting for author approval")
	ErrDocumentBusy             = errors.New("docgov: document edit lease is held by another writer")
	ErrLeaseExpired             = errors.New("docgov: document edit lease has expired")
	ErrLeaseNotHeld             = errors.New("docgov: caller does not hold the document edit lease")
	ErrForceEditNotAllowed      = errors.New("docgov: force_direct_edit requires an approved_by_author proposal and unlocked drafting document")
)

// LeaseHolderType 编辑租约持有者类型
type LeaseHolderType string

const (
	LeaseHolderNone  LeaseHolderType = ""
	LeaseHolderSquad LeaseHolderType = "squad"
	LeaseHolderHuman LeaseHolderType = "human"
)

// DefaultSquadLeaseTTL 小队任务默认租约时长
const DefaultSquadLeaseTTL = 30 * time.Minute

// DefaultHumanLeaseTTL 人工编辑会话默认租约时长
const DefaultHumanLeaseTTL = 15 * time.Minute

// DocumentBusyError 携带租约占用详情，便于 HTTP 409 与 UI 提示
type DocumentBusyError struct {
	DocID      string          `json:"doc_id"`
	HolderType LeaseHolderType `json:"holder_type"`
	HolderID   string          `json:"holder_id"`
	WorkDir    string          `json:"work_dir,omitempty"`
	ExpiresAt  time.Time       `json:"expires_at"`
	Reason     string          `json:"reason"`
}

func (e *DocumentBusyError) Error() string {
	if e.Reason != "" {
		return e.Reason
	}
	return ErrDocumentBusy.Error()
}

func (e *DocumentBusyError) Unwrap() error { return ErrDocumentBusy }

// DocumentState 文档生命周期流转状态
type DocumentState string

const (
	StateDrafting  DocumentState = "drafting"  // 编制中 (草稿)
	StateReviewing DocumentState = "reviewing" // 审核中 (待审核, 锁定)
	StateApproving DocumentState = "approving" // 批准中 (待批准, 锁定)
	StateApproved  DocumentState = "approved"  // 已批准 (归档生效, 终态锁定)
	StateRejected  DocumentState = "rejected"  // 已驳回 (中间状态或流转标记)
)

// UserRole 治理责任人角色 (各有且仅有一个责任人)
type UserRole string

const (
	RoleAuthor   UserRole = "author"   // 编制人
	RoleReviewer UserRole = "reviewer" // 审核人
	RoleApprover UserRole = "approver" // 批准人
	RoleSystem   UserRole = "system"   // 系统/智能体小队
)

// DocumentConfig 受控文档流转与退回配置
type DocumentConfig struct {
	RejectRollbackTo         DocumentState `json:"reject_rollback_to"`          // 驳回退回目标: drafting 或 reviewing
	AllowApproverToReviewer  bool          `json:"allow_approver_to_reviewer"`  // 是否允许批准人退回至审核阶段
	RequireAuthorConfirmOnReject bool      `json:"require_author_confirm_on_reject"` // 驳回退回编制时是否需编制人确认已获悉
}

func DefaultDocumentConfig() DocumentConfig {
	return DocumentConfig{
		RejectRollbackTo:         StateDrafting,
		AllowApproverToReviewer:  true,
		RequireAuthorConfirmOnReject: true,
	}
}

// DocumentRecord 受控文档治理台账实体
type DocumentRecord struct {
	ID             int64          `json:"id"`
	DocID          string         `json:"doc_id"`           // 业务唯一ID，如 doc_proj1_feasibility_reg_v1
	ProjectID      int64          `json:"project_id"`       // 项目ID
	TaskKey        string         `json:"task_key"`         // 任务标识: feasibility_reg, intake, cdo_quote
	Title          string         `json:"title"`            // 标题
	Stage          string         `json:"stage"`            // 阶段: V0.5_feasibility
	Version        int            `json:"version"`          // 版本号
	CurrentState   DocumentState  `json:"current_state"`    // drafting, reviewing, approving, approved
	IsLocked       bool           `json:"is_locked"`        // reviewing/approving/approved 期间锁定
	IsTemplateOnly bool           `json:"is_template_only"` // 是否仅为骨架模板 (模板状态即使查看也不算认领)
	ContentSHA256  string         `json:"content_sha256"`   // 当前版本正文哈希
	WorkDir        string         `json:"work_dir"`         // 关联工作区相对路径

	// 三级法定责任人 (各有且仅有一个)
	AuthorID     int64  `json:"author_id"`
	AuthorName   string `json:"author_name"`
	ReviewerID   int64  `json:"reviewer_id"`
	ReviewerName string `json:"reviewer_name"`
	ApproverID   int64  `json:"approver_id"`
	ApproverName string `json:"approver_name"`

	// 认领状态 (Claiming State)
	AuthorClaimed       bool       `json:"author_claimed"`        // 编制人是否已认领 (非模板状态查看/编辑后为 true)
	AuthorClaimedAt     *time.Time `json:"author_claimed_at"`
	AuthorLastViewedAt  *time.Time `json:"author_last_viewed_at"`
	AuthorLastEditedAt  *time.Time `json:"author_last_edited_at"`
	ReviewerClaimed     bool       `json:"reviewer_claimed"`      // 审核人是否已认领审核
	ReviewerClaimedAt   *time.Time `json:"reviewer_claimed_at"`
	ApproverClaimed     bool       `json:"approver_claimed"`      // 批准人是否已认领批准
	ApproverClaimedAt   *time.Time `json:"approver_claimed_at"`

	// 驳回与决议记录
	LastRejectedReason string     `json:"last_rejected_reason"`
	LastRejectedByRole string     `json:"last_rejected_by_role"`
	LastRejectedByName string     `json:"last_rejected_by_name"`
	LastRejectedAt     *time.Time `json:"last_rejected_at"`
	ApprovedAt         *time.Time `json:"approved_at"`

	// 编辑租约 (运行时互斥，正交于 IsLocked)
	LeaseHolderType  LeaseHolderType `json:"lease_holder_type,omitempty"`
	LeaseHolderID    string          `json:"lease_holder_id,omitempty"`
	LeaseWorkDir     string          `json:"lease_work_dir,omitempty"`
	LeaseExpiresAt   *time.Time      `json:"lease_expires_at,omitempty"`
	LeaseHeartbeatAt *time.Time      `json:"lease_heartbeat_at,omitempty"`

	Config    DocumentConfig `json:"config"`
	CreatedAt time.Time      `json:"created_at"`
	UpdatedAt time.Time      `json:"updated_at"`
}

// HasActiveLease 判断文档是否持有未过期的编辑租约
func (d *DocumentRecord) HasActiveLease(now time.Time) bool {
	if d == nil || d.LeaseHolderType == LeaseHolderNone || d.LeaseHolderType == "" {
		return false
	}
	if d.LeaseExpiresAt == nil {
		return false
	}
	return d.LeaseExpiresAt.After(now)
}

// ClearLease 清空租约字段（内存）
func (d *DocumentRecord) ClearLease() {
	d.LeaseHolderType = LeaseHolderNone
	d.LeaseHolderID = ""
	d.LeaseWorkDir = ""
	d.LeaseExpiresAt = nil
	d.LeaseHeartbeatAt = nil
}

// CommentType 批注类型
type CommentType string

const (
	CommentGeneral    CommentType = "comment"       // 普通批注
	CommentSuggestion CommentType = "suggestion"    // 修改建议
	CommentRejection  CommentType = "reject_reason" // 驳回原因
)

// DocumentComment 批注与修改意见实体
type DocumentComment struct {
	ID            int64       `json:"id"`
	DocID         string      `json:"doc_id"`
	UserID        int64       `json:"user_id"`
	UserName      string      `json:"user_name"`
	UserRole      UserRole    `json:"user_role"`      // author, reviewer, approver
	TargetSection string      `json:"target_section"` // 目标章节锚点，如 "## 结论"
	CommentType   CommentType `json:"comment_type"`   // comment, suggestion, reject_reason
	Content       string      `json:"content"`        // 意见内容
	Status        string      `json:"status"`         // open, resolved, accepted
	CreatedAt     time.Time   `json:"created_at"`
}

// ProposalStatus 变更提案状态
type ProposalStatus string

const (
	ProposalPendingAuthorApproval ProposalStatus = "pending_author_approval" // 待编制人拍板
	ProposalApprovedByAuthor      ProposalStatus = "approved_by_author"       // 编制人已同意修改
	ProposalRejectedByAuthor      ProposalStatus = "rejected_by_author"       // 编制人已拒绝修改
	ProposalApplied               ProposalStatus = "applied"                  // 已应用执行
)

// ChangeProposal 针对已认领文档的智能体修改变更提案实体
type ChangeProposal struct {
	ID                   int64          `json:"id"`
	ProposalID           string         `json:"proposal_id"`
	DocID                string         `json:"doc_id"`
	ProjectID            int64          `json:"project_id"`
	TriggeredBy          string         `json:"triggered_by"`           // agent_squad, stage_sync, upstream_change
	ProposedChanges      string         `json:"proposed_changes"`       // 有哪些地方要改 (变更内容与对比摘要)
	ImpactAnalysis       string         `json:"impact_analysis"`        // 影响会是什么 (范围、上下游依赖)
	RiskAssessment       string         `json:"risk_assessment"`        // 可能产生的风险 (合规、工时、预算)
	Status               ProposalStatus `json:"status"`                 // pending_author_approval...
	AuthorDecisionReason string         `json:"author_decision_reason"` // 编制人批准/拒绝原因
	DecidedAt            *time.Time     `json:"decided_at"`
	CreatedAt            time.Time      `json:"created_at"`
}

// AuditLog 文档治理生命周期审计跟踪
type AuditLog struct {
	ID        int64          `json:"id"`
	DocID     string         `json:"doc_id"`
	Action    string         `json:"action"` // view, edit, claim, submit_review, review_approve, review_reject...
	ActorID   int64          `json:"actor_id"`
	ActorName string         `json:"actor_name"`
	ActorRole UserRole       `json:"actor_role"`
	FromState DocumentState  `json:"from_state"`
	ToState   DocumentState  `json:"to_state"`
	Details   map[string]any `json:"details"`
	CreatedAt time.Time      `json:"created_at"`
}