package docduty

import (
	"fmt"
	"strings"
)

const (
	DutyNone     = ""
	DutyAuthor   = "author"
	DutyReviewer = "reviewer"
	DutyApprover = "approver"
	StatusActive = "active"
)

// Holder 某一文档职责的用户。
type Holder struct {
	UserID int64
	Name   string
}

// Binding 一份受控文档应采用的编制/审核/批准职责。
type Binding struct {
	Author   Holder
	Reviewer Holder
	Approver Holder
}

// Member 项目成员快照（访问角色与文档职责分离）。
type Member struct {
	UserID       int64
	Name         string
	Status       string
	ProjectRole  string
	DocumentDuty string
}

// RequestDuties 任务请求里客户端声称的职责；仅当该用户是在任成员时才可采用。
type RequestDuties struct {
	AuthorID     int64
	AuthorName   string
	ReviewerID   int64
	ReviewerName string
	ApproverID   int64
	ApproverName string
}

// NormalizeDocumentDuty 校验 document_duty。空串表示无文档职责。
func NormalizeDocumentDuty(raw string) (string, error) {
	duty := strings.TrimSpace(strings.ToLower(raw))
	switch duty {
	case DutyNone, DutyAuthor, DutyReviewer, DutyApprover:
		return duty, nil
	default:
		return "", fmt.Errorf("docduty: invalid document_duty %q", raw)
	}
}

// ActiveMemberIDs 在任成员（含创建者）。
func ActiveMemberIDs(members []Member, creator Holder) map[int64]struct{} {
	ids := make(map[int64]struct{}, len(members)+1)
	if creator.UserID > 0 {
		ids[creator.UserID] = struct{}{}
	}
	for _, m := range members {
		if m.UserID > 0 && (m.Status == "" || m.Status == StatusActive) {
			ids[m.UserID] = struct{}{}
		}
	}
	return ids
}

func isActiveMember(m Member) bool {
	return m.UserID > 0 && (m.Status == "" || m.Status == StatusActive)
}

func dutyHolder(members []Member, duty string) Holder {
	var found Holder
	for _, m := range members {
		if !isActiveMember(m) || m.DocumentDuty != duty {
			continue
		}
		found = Holder{UserID: m.UserID, Name: strings.TrimSpace(m.Name)}
	}
	return found
}

func pickMember(reqID int64, reqName string, memberIDs map[int64]struct{}, members []Member) Holder {
	if reqID <= 0 {
		return Holder{}
	}
	if _, ok := memberIDs[reqID]; !ok {
		return Holder{}
	}
	name := strings.TrimSpace(reqName)
	for _, m := range members {
		if m.UserID == reqID && isActiveMember(m) && strings.TrimSpace(m.Name) != "" {
			name = strings.TrimSpace(m.Name)
			break
		}
	}
	return Holder{UserID: reqID, Name: name}
}

// Resolve 以项目 document_duty 为权威。禁止回落到硬编码 2/3。
// author：指定编制人 → 创建者 → 请求 id（须为成员）。
// reviewer/approver：指定职责 → 请求 id（须为成员）→ 空。
func Resolve(members []Member, creator Holder, req RequestDuties) Binding {
	memberIDs := ActiveMemberIDs(members, creator)
	out := Binding{}

	if h := dutyHolder(members, DutyAuthor); h.UserID > 0 {
		out.Author = h
	} else if creator.UserID > 0 {
		out.Author = creator
	} else {
		out.Author = pickMember(req.AuthorID, req.AuthorName, memberIDs, members)
	}

	if h := dutyHolder(members, DutyReviewer); h.UserID > 0 {
		out.Reviewer = h
	} else {
		out.Reviewer = pickMember(req.ReviewerID, req.ReviewerName, memberIDs, members)
	}

	if h := dutyHolder(members, DutyApprover); h.UserID > 0 {
		out.Approver = h
	} else {
		out.Approver = pickMember(req.ApproverID, req.ApproverName, memberIDs, members)
	}

	return out
}

// DutyMissing 当前职责缺失或指向非成员（含历史硬编码占位 id）。
func DutyMissing(currentID int64, memberIDs map[int64]struct{}) bool {
	if currentID <= 0 {
		return true
	}
	_, ok := memberIDs[currentID]
	return !ok
}

func healSlot(current, assigned Holder, memberIDs map[int64]struct{}, clearInactive bool) (Holder, bool) {
	if assigned.UserID > 0 {
		if current.UserID == assigned.UserID && current.Name == assigned.Name {
			return current, false
		}
		return assigned, true
	}
	if current.UserID <= 0 {
		return current, false
	}
	if _, ok := memberIDs[current.UserID]; ok {
		return current, false
	}
	if !clearInactive {
		return current, false
	}
	return Holder{}, true
}

// HealBinding 以项目 document_duty 为权威。assigned 非零则对齐（错 ID 或同 ID 旧名称）。
// assigned 为空时：审核/批准仅清空已退出或非成员的失效 holder；在任成员保留以兼容未初始化 duty 的旧项目。
// 编制槽位即使 assigned 为空也不清空，避免无意去掉 owner/author。
func HealBinding(current, assigned Binding, memberIDs map[int64]struct{}) (Binding, bool) {
	out := current
	changed := false
	if next, ok := healSlot(current.Author, assigned.Author, memberIDs, false); ok {
		out.Author = next
		changed = true
	}
	if next, ok := healSlot(current.Reviewer, assigned.Reviewer, memberIDs, true); ok {
		out.Reviewer = next
		changed = true
	}
	if next, ok := healSlot(current.Approver, assigned.Approver, memberIDs, true); ok {
		out.Approver = next
		changed = true
	}
	return out, changed
}