package docgov

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"chat-agent-system/internal/docduty"
)

// WorkflowDocumentSummary 项目工作流受控文档列表项。
type WorkflowDocumentSummary struct {
	DocID            string          `json:"doc_id"`
	ProjectID        int64           `json:"project_id"`
	TaskKey          string          `json:"task_key"`
	Title            string          `json:"title"`
	LifecycleState   DocumentState   `json:"lifecycle_state"`
	IsTemplateOnly   bool            `json:"is_template_only"`
	ContentSHA256    string          `json:"content_sha256"`
	WorkDir          string          `json:"work_dir,omitempty"`
	Version          int             `json:"version"`
	UpdatedAt        string          `json:"updated_at,omitempty"`
	LeaseHolderType  LeaseHolderType `json:"lease_holder_type,omitempty"`
	LeaseHolderID    string          `json:"lease_holder_id,omitempty"`
	LeaseExpiresAt   *time.Time      `json:"lease_expires_at,omitempty"`
	LeaseHeartbeatAt *time.Time      `json:"lease_heartbeat_at,omitempty"`
	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"`
}

// DocumentContent 受控文档正文读取结果。
type DocumentContent struct {
	DocID          string `json:"doc_id"`
	Version        int    `json:"version"`
	ContentSHA256  string `json:"content_sha256"`
	Markdown       string `json:"markdown"`
	IsTemplateOnly bool   `json:"is_template_only"`
}

// ListWorkflowDocumentsByProject 列出项目下工作流受控文档（task_key 非空）。
func (e *GovernanceEngine) ListWorkflowDocumentsByProject(ctx context.Context, projectID int64) ([]WorkflowDocumentSummary, error) {
	if projectID <= 0 {
		return nil, fmt.Errorf("invalid project_id")
	}

	if e.pool != nil {
		if _, _, err := docduty.HealProjectDocuments(ctx, e.pool, projectID); err != nil {
			return nil, fmt.Errorf("heal project document duties: %w", err)
		}
		rows, err := e.pool.Query(ctx, `
			SELECT doc_id, project_id, task_key, title, current_state, is_template_only,
			       COALESCE(content_sha256, ''), COALESCE(work_dir, ''), version, updated_at,
			       COALESCE(lease_holder_type, ''), COALESCE(lease_holder_id, ''),
			       lease_expires_at, lease_heartbeat_at,
			       COALESCE(author_id, 0), COALESCE(author_name, ''),
			       COALESCE(reviewer_id, 0), COALESCE(reviewer_name, ''),
			       COALESCE(approver_id, 0), COALESCE(approver_name, '')
			FROM document_records
			WHERE project_id = $1 AND task_key <> ''
			ORDER BY task_key ASC, doc_id ASC
		`, projectID)
		if err != nil {
			return nil, err
		}
		defer rows.Close()
		out := make([]WorkflowDocumentSummary, 0)
		for rows.Next() {
			var item WorkflowDocumentSummary
			var state string
			var updatedAt time.Time
			if err := rows.Scan(
				&item.DocID, &item.ProjectID, &item.TaskKey, &item.Title, &state,
				&item.IsTemplateOnly, &item.ContentSHA256, &item.WorkDir, &item.Version, &updatedAt,
				&item.LeaseHolderType, &item.LeaseHolderID, &item.LeaseExpiresAt, &item.LeaseHeartbeatAt,
				&item.AuthorID, &item.AuthorName, &item.ReviewerID, &item.ReviewerName,
				&item.ApproverID, &item.ApproverName,
			); err != nil {
				return nil, err
			}
			item.LifecycleState = DocumentState(state)
			if !updatedAt.IsZero() {
				item.UpdatedAt = updatedAt.Format(time.RFC3339)
			}
			out = append(out, item)
		}
		return out, rows.Err()
	}

	e.mu.Lock()
	defer e.mu.Unlock()
	out := make([]WorkflowDocumentSummary, 0)
	for _, doc := range e.memDocs {
		if doc.ProjectID == projectID && doc.TaskKey != "" {
			out = append(out, WorkflowDocumentSummary{
				DocID:            doc.DocID,
				ProjectID:        doc.ProjectID,
				TaskKey:          doc.TaskKey,
				Title:            doc.Title,
				LifecycleState:   doc.CurrentState,
				IsTemplateOnly:   doc.IsTemplateOnly,
				ContentSHA256:    doc.ContentSHA256,
				WorkDir:          doc.WorkDir,
				Version:          doc.Version,
				LeaseHolderType:  doc.LeaseHolderType,
				LeaseHolderID:    doc.LeaseHolderID,
				LeaseExpiresAt:   doc.LeaseExpiresAt,
				LeaseHeartbeatAt: doc.LeaseHeartbeatAt,
				AuthorID:         doc.AuthorID,
				AuthorName:       doc.AuthorName,
				ReviewerID:       doc.ReviewerID,
				ReviewerName:     doc.ReviewerName,
				ApproverID:       doc.ApproverID,
				ApproverName:     doc.ApproverName,
			})
		}
	}
	return out, nil
}

// ReadDocumentContent 读取受控文档 output.md 并返回 typed ContentError。
// 记录不存在才是 DOCUMENT_NOT_FOUND；缺文件/空文件/哈希冲突不得伪装成 404。
func (e *GovernanceEngine) ReadDocumentContent(ctx context.Context, docID string, repoRoot string) (*DocumentContent, error) {
	doc, err := e.GetDocument(ctx, docID)
	if err != nil {
		if errors.Is(err, ErrDocumentNotFound) {
			return nil, NewContentError(ErrCodeDocumentNotFound, err, false, false)
		}
		return nil, err
	}
	if doc.WorkDir == "" {
		return nil, NewContentError(ErrCodeProjectionMissing, ErrContentProjectionMissing, false, true)
	}

	workDir := doc.WorkDir
	if !filepath.IsAbs(workDir) && repoRoot != "" {
		workDir = filepath.Join(repoRoot, workDir)
	}
	path := filepath.Join(workDir, "output.md")
	data, err := os.ReadFile(path)
	if err != nil {
		ce := NewContentError(ErrCodeProjectionMissing, fmt.Errorf("%w: %v", ErrContentProjectionMissing, err), true, true)
		ce.RecordSHA = doc.ContentSHA256
		return nil, ce
	}
	if len(data) == 0 {
		ce := NewContentError(ErrCodeProjectionEmpty, ErrContentProjectionEmpty, false, true)
		ce.RecordSHA = doc.ContentSHA256
		return nil, ce
	}

	sum := sha256.Sum256(data)
	shaStr := hex.EncodeToString(sum[:])
	if doc.ContentSHA256 != "" && !strings.EqualFold(doc.ContentSHA256, shaStr) {
		ce := NewContentError(ErrCodeIntegrityMismatch, fmt.Errorf("%w: record=%s file=%s", ErrContentIntegrityMismatch, doc.ContentSHA256, shaStr), false, true)
		ce.RecordSHA = doc.ContentSHA256
		ce.FileSHA = shaStr
		return nil, ce
	}

	return &DocumentContent{
		DocID:          doc.DocID,
		Version:        doc.Version,
		ContentSHA256:  shaStr,
		Markdown:       string(data),
		IsTemplateOnly: doc.IsTemplateOnly,
	}, nil
}