package app

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/geo-platform/tenant-api/internal/shared/auditlog"
	"github.com/geo-platform/tenant-api/internal/shared/auth"
	"github.com/geo-platform/tenant-api/internal/shared/contentstats"
	"github.com/geo-platform/tenant-api/internal/shared/middleware"
	"github.com/geo-platform/tenant-api/internal/shared/objectstorage"
	"github.com/geo-platform/tenant-api/internal/shared/response"
)

type ArticleService struct {
	pool          *pgxpool.Pool
	auditLogs     *auditlog.AsyncWriter
	objectStorage objectstorage.Client
}

func NewArticleService(pool *pgxpool.Pool, auditLogs *auditlog.AsyncWriter, objectStorage objectstorage.Client) *ArticleService {
	return &ArticleService{pool: pool, auditLogs: auditLogs, objectStorage: objectStorage}
}

const maxArticleImageSizeBytes = 10 * 1024 * 1024

var supportedArticleImageExtensions = map[string]string{
	"image/gif":  "gif",
	"image/jpeg": "jpg",
	"image/png":  "png",
	"image/webp": "webp",
}

type ArticleListParams struct {
	Page           int
	PageSize       int
	GenerateStatus *string
	PublishStatus  *string
	SourceType     *string
	GenerationMode *string
	TemplateID     *int64
	PromptRuleID   *int64
	Keyword        *string
	CreatedFrom    *time.Time
	CreatedTo      *time.Time
}

type ArticleListItem struct {
	ID                     int64     `json:"id"`
	SourceType             string    `json:"source_type"`
	TemplateID             *int64    `json:"template_id"`
	TemplateName           *string   `json:"template_name"`
	PromptRuleID           *int64    `json:"prompt_rule_id"`
	PromptRuleName         *string   `json:"prompt_rule_name"`
	GenerationMode         *string   `json:"generation_mode"`
	Platforms              []string  `json:"platforms"`
	GenerateStatus         string    `json:"generate_status"`
	PublishStatus          string    `json:"publish_status"`
	Title                  *string   `json:"title"`
	GenerationErrorMessage *string   `json:"generation_error_message"`
	WordCount              int       `json:"word_count"`
	SourceLabel            *string   `json:"source_label"`
	CreatedAt              time.Time `json:"created_at"`
}

type ArticleListResponse struct {
	Items    []ArticleListItem `json:"items"`
	Total    int64             `json:"total"`
	Page     int               `json:"page"`
	PageSize int               `json:"page_size"`
}

func (s *ArticleService) List(ctx context.Context, params ArticleListParams) (*ArticleListResponse, error) {
	actor := auth.MustActor(ctx)
	sourceType := params.SourceType

	if params.Page < 1 {
		params.Page = 1
	}
	if params.PageSize < 1 || params.PageSize > 100 {
		params.PageSize = 20
	}
	offset := (params.Page - 1) * params.PageSize

	// Count
	var total int64
	countArgs := []interface{}{actor.TenantID}
	countQuery := `SELECT COUNT(*) FROM articles a
		LEFT JOIN article_versions av ON av.id = a.current_version_id
		LEFT JOIN prompt_rules pr ON pr.id = a.prompt_rule_id
		LEFT JOIN LATERAL (
			SELECT input_params_json
			FROM generation_tasks
			WHERE article_id = a.id
			ORDER BY created_at DESC
			LIMIT 1
		) gt ON true
		WHERE a.tenant_id = $1 AND a.deleted_at IS NULL`
	argIdx := 2

	if params.GenerateStatus != nil {
		countQuery += ` AND a.generate_status = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.GenerateStatus)
		argIdx++
	}
	if params.PublishStatus != nil {
		countQuery += ` AND a.publish_status = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.PublishStatus)
		argIdx++
	}
	if sourceType != nil {
		countQuery += ` AND a.source_type = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *sourceType)
		argIdx++
	}
	if params.GenerationMode != nil {
		countQuery += ` AND a.source_type = 'custom_generation' AND COALESCE(NULLIF(gt.input_params_json ->> 'generation_mode', ''), 'instant') = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.GenerationMode)
		argIdx++
	}
	if params.TemplateID != nil {
		countQuery += ` AND a.template_id = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.TemplateID)
		argIdx++
	}
	if params.PromptRuleID != nil {
		countQuery += ` AND a.prompt_rule_id = $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.PromptRuleID)
		argIdx++
	}
	if params.Keyword != nil {
		countQuery += ` AND COALESCE(av.title, NULLIF(a.wizard_state_json ->> 'title', ''), NULLIF(gt.input_params_json ->> 'title', '')) ILIKE '%' || $` + strconv.Itoa(argIdx) + ` || '%'`
		countArgs = append(countArgs, *params.Keyword)
		argIdx++
	}
	if params.CreatedFrom != nil {
		countQuery += ` AND a.created_at >= $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.CreatedFrom)
		argIdx++
	}
	if params.CreatedTo != nil {
		countQuery += ` AND a.created_at <= $` + strconv.Itoa(argIdx)
		countArgs = append(countArgs, *params.CreatedTo)
		argIdx++
	}

	if err := s.pool.QueryRow(ctx, countQuery, countArgs...).Scan(&total); err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to count articles")
	}

	// List
	listQuery := `SELECT a.id, a.source_type, a.template_id, a.prompt_rule_id, a.generate_status, a.publish_status, a.created_at,
		COALESCE(av.title, NULLIF(a.wizard_state_json ->> 'title', ''), NULLIF(gt.input_params_json ->> 'title', '')), gt.error_message, av.markdown_content, COALESCE(av.word_count, 0), av.source_label, t.template_name, pr.name, a.wizard_state_json, gt.input_params_json
		FROM articles a
		LEFT JOIN article_versions av ON av.id = a.current_version_id
		LEFT JOIN article_templates t ON t.id = a.template_id
		LEFT JOIN prompt_rules pr ON pr.id = a.prompt_rule_id
		LEFT JOIN LATERAL (
			SELECT error_message, input_params_json
			FROM generation_tasks
			WHERE article_id = a.id
			ORDER BY created_at DESC
			LIMIT 1
		) gt ON true
		WHERE a.tenant_id = $1 AND a.deleted_at IS NULL`
	listArgs := []interface{}{actor.TenantID}
	listIdx := 2

	if params.GenerateStatus != nil {
		listQuery += ` AND a.generate_status = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.GenerateStatus)
		listIdx++
	}
	if params.PublishStatus != nil {
		listQuery += ` AND a.publish_status = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.PublishStatus)
		listIdx++
	}
	if sourceType != nil {
		listQuery += ` AND a.source_type = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *sourceType)
		listIdx++
	}
	if params.GenerationMode != nil {
		listQuery += ` AND a.source_type = 'custom_generation' AND COALESCE(NULLIF(gt.input_params_json ->> 'generation_mode', ''), 'instant') = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.GenerationMode)
		listIdx++
	}
	if params.TemplateID != nil {
		listQuery += ` AND a.template_id = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.TemplateID)
		listIdx++
	}
	if params.PromptRuleID != nil {
		listQuery += ` AND a.prompt_rule_id = $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.PromptRuleID)
		listIdx++
	}
	if params.Keyword != nil {
		listQuery += ` AND COALESCE(av.title, NULLIF(a.wizard_state_json ->> 'title', ''), NULLIF(gt.input_params_json ->> 'title', '')) ILIKE '%' || $` + strconv.Itoa(listIdx) + ` || '%'`
		listArgs = append(listArgs, *params.Keyword)
		listIdx++
	}
	if params.CreatedFrom != nil {
		listQuery += ` AND a.created_at >= $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.CreatedFrom)
		listIdx++
	}
	if params.CreatedTo != nil {
		listQuery += ` AND a.created_at <= $` + strconv.Itoa(listIdx)
		listArgs = append(listArgs, *params.CreatedTo)
		listIdx++
	}

	listQuery += ` ORDER BY a.created_at DESC LIMIT $` + strconv.Itoa(listIdx) + ` OFFSET $` + strconv.Itoa(listIdx+1)
	listArgs = append(listArgs, params.PageSize, offset)

	rows, err := s.pool.Query(ctx, listQuery, listArgs...)
	if err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to list articles")
	}
	defer rows.Close()

	var items []ArticleListItem
	for rows.Next() {
		var item ArticleListItem
		var dbSourceType string
		var markdownContent *string
		var wizardStateJSON []byte
		var inputParamsJSON []byte
		if err := rows.Scan(&item.ID, &dbSourceType, &item.TemplateID, &item.PromptRuleID, &item.GenerateStatus, &item.PublishStatus, &item.CreatedAt,
			&item.Title, &item.GenerationErrorMessage, &markdownContent, &item.WordCount, &item.SourceLabel, &item.TemplateName, &item.PromptRuleName, &wizardStateJSON, &inputParamsJSON); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		item.SourceType = dbSourceType
		item.GenerationMode = resolveArticleGenerationMode(dbSourceType, inputParamsJSON)
		item.Platforms = resolveArticlePlatforms(wizardStateJSON, inputParamsJSON)
		item.WordCount = resolveWordCount(markdownContent, item.WordCount)
		items = append(items, item)
	}
	if items == nil {
		items = []ArticleListItem{}
	}

	return &ArticleListResponse{Items: items, Total: total, Page: params.Page, PageSize: params.PageSize}, nil
}

type ArticleDetailResponse struct {
	ID                     int64                  `json:"id"`
	SourceType             string                 `json:"source_type"`
	TemplateID             *int64                 `json:"template_id"`
	TemplateName           *string                `json:"template_name"`
	GenerationMode         *string                `json:"generation_mode"`
	Platforms              []string               `json:"platforms"`
	GenerateStatus         string                 `json:"generate_status"`
	PublishStatus          string                 `json:"publish_status"`
	Title                  *string                `json:"title"`
	HTMLContent            *string                `json:"html_content"`
	MarkdownContent        *string                `json:"markdown_content"`
	WordCount              int                    `json:"word_count"`
	SourceLabel            *string                `json:"source_label"`
	VersionNo              *int                   `json:"version_no"`
	GenerationErrorMessage *string                `json:"generation_error_message"`
	WizardState            map[string]interface{} `json:"wizard_state,omitempty"`
	CreatedAt              time.Time              `json:"created_at"`
}

func (s *ArticleService) Detail(ctx context.Context, id int64) (*ArticleDetailResponse, error) {
	actor := auth.MustActor(ctx)
	var d ArticleDetailResponse
	var dbSourceType string

	var wizardStateJSON []byte
	var inputParamsJSON []byte
	err := s.pool.QueryRow(ctx, `
		SELECT a.id, a.source_type, a.template_id, a.generate_status, a.publish_status, a.created_at,
		       COALESCE(av.title, NULLIF(a.wizard_state_json ->> 'title', ''), NULLIF(gt.input_params_json ->> 'title', '')), av.html_content, av.markdown_content, COALESCE(av.word_count, 0), av.source_label, av.version_no,
		       t.template_name, gt.error_message, a.wizard_state_json, gt.input_params_json
		FROM articles a
		LEFT JOIN article_versions av ON av.id = a.current_version_id
		LEFT JOIN article_templates t ON t.id = a.template_id
		LEFT JOIN LATERAL (
			SELECT error_message, input_params_json
			FROM generation_tasks
			WHERE article_id = a.id
			ORDER BY created_at DESC
			LIMIT 1
		) gt ON true
		WHERE a.id = $1 AND a.tenant_id = $2 AND a.deleted_at IS NULL
	`, id, actor.TenantID).Scan(&d.ID, &dbSourceType, &d.TemplateID, &d.GenerateStatus, &d.PublishStatus, &d.CreatedAt,
		&d.Title, &d.HTMLContent, &d.MarkdownContent, &d.WordCount, &d.SourceLabel, &d.VersionNo, &d.TemplateName, &d.GenerationErrorMessage, &wizardStateJSON, &inputParamsJSON)
	if err != nil {
		return nil, response.ErrNotFound(40411, "article_not_found", "article not found")
	}
	d.SourceType = dbSourceType
	if len(wizardStateJSON) > 0 {
		d.WizardState = map[string]interface{}{}
		_ = json.Unmarshal(wizardStateJSON, &d.WizardState)
	}
	d.GenerationMode = resolveArticleGenerationMode(dbSourceType, inputParamsJSON)
	d.Platforms = resolveArticlePlatforms(wizardStateJSON, inputParamsJSON)
	d.WordCount = resolveWordCount(d.MarkdownContent, d.WordCount)
	return &d, nil
}

type UpdateArticleRequest struct {
	Title           string   `json:"title"`
	MarkdownContent string   `json:"markdown_content"`
	Platforms       []string `json:"platforms"`
}

type ArticleImageUploadResponse struct {
	URL         string `json:"url"`
	ObjectKey   string `json:"object_key"`
	ContentType string `json:"content_type"`
	SizeBytes   int64  `json:"size_bytes"`
}

func (s *ArticleService) Update(ctx context.Context, id int64, req UpdateArticleRequest) (*ArticleDetailResponse, error) {
	actor := auth.MustActor(ctx)

	title := strings.TrimSpace(req.Title)
	if title == "" {
		return nil, response.ErrBadRequest(40012, "article_title_required", "article title is required")
	}

	markdown := strings.TrimSpace(req.MarkdownContent)

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to begin article update transaction")
	}
	defer tx.Rollback(ctx)

	var generateStatus string
	var wizardStateJSON []byte
	err = tx.QueryRow(ctx, `
		SELECT generate_status, wizard_state_json
		FROM articles
		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
		FOR UPDATE
	`, id, actor.TenantID).Scan(&generateStatus, &wizardStateJSON)
	if err != nil {
		return nil, response.ErrNotFound(40411, "article_not_found", "article not found")
	}

	if generateStatus != "completed" {
		return nil, response.ErrConflict(40912, "article_not_editable", "only completed articles can be edited")
	}

	var nextVersionNo int
	if err := tx.QueryRow(ctx, `
		SELECT COALESCE(MAX(version_no), 0) + 1
		FROM article_versions
		WHERE article_id = $1
	`, id).Scan(&nextVersionNo); err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to resolve next article version")
	}

	wordCount := countArticleWords(markdown)
	sourceLabel := "手动编辑"
	nextWizardStateJSON, err := mergeArticleWizardState(wizardStateJSON, title, req.Platforms)
	if err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to update article metadata")
	}

	var versionID int64
	if err := tx.QueryRow(ctx, `
		INSERT INTO article_versions (article_id, version_no, title, html_content, markdown_content, word_count, source_label)
		VALUES ($1, $2, $3, NULL, $4, $5, $6)
		RETURNING id
	`, id, nextVersionNo, title, markdown, wordCount, sourceLabel).Scan(&versionID); err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to create article version")
	}

	tag, err := tx.Exec(ctx, `
		UPDATE articles
		SET current_version_id = $1,
		    generate_status = 'completed',
		    publish_status = 'unpublished',
		    wizard_state_json = $4,
		    updated_at = NOW()
		WHERE id = $2 AND tenant_id = $3 AND deleted_at IS NULL
	`, versionID, id, actor.TenantID, nextWizardStateJSON)
	if err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to update article")
	}
	if tag.RowsAffected() == 0 {
		return nil, response.ErrNotFound(40411, "article_not_found", "article not found")
	}

	if err := tx.Commit(ctx); err != nil {
		return nil, response.ErrInternal(50012, "update_failed", "failed to commit article update")
	}

	return s.Detail(ctx, id)
}

func (s *ArticleService) UploadImage(
	ctx context.Context,
	articleID int64,
	fileName string,
	content []byte,
) (*ArticleImageUploadResponse, error) {
	actor := auth.MustActor(ctx)

	if err := s.objectStorage.Validate(); err != nil {
		return nil, response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
	}
	if len(content) == 0 {
		return nil, response.ErrBadRequest(40016, "invalid_image", "image file is required")
	}
	if len(content) > maxArticleImageSizeBytes {
		return nil, response.ErrBadRequest(40017, "article_image_too_large", "image size cannot exceed 10 MB")
	}

	contentType := http.DetectContentType(content)
	resolvedExt, ok := supportedArticleImageExtensions[contentType]
	if !ok {
		return nil, response.ErrBadRequest(40018, "article_image_type_not_supported", "only PNG, JPG, GIF, and WebP images are supported")
	}

	generateStatus, err := s.getEditableArticleStatus(ctx, articleID, actor.TenantID)
	if err != nil {
		return nil, err
	}
	if generateStatus != "completed" {
		return nil, response.ErrConflict(40912, "article_not_editable", "only completed articles can be edited")
	}

	objectKey := buildArticleImageObjectKey(actor.TenantID, articleID, fileName, resolvedExt)
	if err := s.objectStorage.PutBytes(ctx, objectKey, content, contentType); err != nil {
		if errors.Is(err, objectstorage.ErrNotConfigured) {
			return nil, response.ErrServiceUnavailable(50303, "object_storage_unavailable", "object storage is not configured")
		}
		return nil, response.ErrInternal(50013, "article_image_upload_failed", "failed to upload article image")
	}

	return &ArticleImageUploadResponse{
		URL:         "",
		ObjectKey:   objectKey,
		ContentType: contentType,
		SizeBytes:   int64(len(content)),
	}, nil
}

type VersionItem struct {
	ID          int64     `json:"id"`
	VersionNo   int       `json:"version_no"`
	Title       *string   `json:"title"`
	WordCount   int       `json:"word_count"`
	SourceLabel *string   `json:"source_label"`
	CreatedAt   time.Time `json:"created_at"`
}

func (s *ArticleService) Versions(ctx context.Context, articleID int64) ([]VersionItem, error) {
	actor := auth.MustActor(ctx)

	// Verify ownership
	var exists bool
	_ = s.pool.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM articles WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL)`,
		articleID, actor.TenantID).Scan(&exists)
	if !exists {
		return nil, response.ErrNotFound(40411, "article_not_found", "article not found")
	}

	rows, err := s.pool.Query(ctx, `
		SELECT id, version_no, title, markdown_content, word_count, source_label, created_at
		FROM article_versions WHERE article_id = $1 ORDER BY version_no DESC
	`, articleID)
	if err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to list versions")
	}
	defer rows.Close()

	var versions []VersionItem
	for rows.Next() {
		var v VersionItem
		var markdownContent *string
		if err := rows.Scan(&v.ID, &v.VersionNo, &v.Title, &markdownContent, &v.WordCount, &v.SourceLabel, &v.CreatedAt); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		v.WordCount = resolveWordCount(markdownContent, v.WordCount)
		versions = append(versions, v)
	}
	if versions == nil {
		versions = []VersionItem{}
	}
	return versions, nil
}

func (s *ArticleService) Delete(ctx context.Context, id int64) error {
	actor := auth.MustActor(ctx)

	// Read before_json for audit
	var beforeJSON []byte
	_ = s.pool.QueryRow(ctx, `SELECT row_to_json(a) FROM articles a WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL`,
		id, actor.TenantID).Scan(&beforeJSON)

	tag, err := s.pool.Exec(ctx, `
		UPDATE articles SET deleted_at = NOW(), updated_at = NOW()
		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
	`, id, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40411, "article_not_found", "article not found")
	}

	result := "success"
	resourceType := "article"
	requestID := middleware.RequestIDFromContext(ctx)
	s.auditLogs.Log(auditlog.Entry{
		OperatorID:   actor.UserID,
		TenantID:     &actor.TenantID,
		Module:       "article",
		Action:       "delete",
		ResourceType: &resourceType,
		ResourceID:   &id,
		RequestID:    nilIfEmptyString(requestID),
		BeforeJSON:   json.RawMessage(beforeJSON),
		Result:       &result,
	})

	return nil
}

func countArticleWords(input string) int {
	return contentstats.CountWords(input)
}

func (s *ArticleService) getEditableArticleStatus(ctx context.Context, articleID int64, tenantID int64) (string, error) {
	var generateStatus string
	if err := s.pool.QueryRow(ctx, `
		SELECT generate_status
		FROM articles
		WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
	`, articleID, tenantID).Scan(&generateStatus); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return "", response.ErrNotFound(40411, "article_not_found", "article not found")
		}
		return "", response.ErrInternal(50013, "article_lookup_failed", "failed to query article state")
	}
	return generateStatus, nil
}

func buildArticleImageObjectKey(tenantID int64, articleID int64, fileName string, fallbackExt string) string {
	now := time.Now().UTC()
	extension := normalizeArticleImageExtension(fileName, fallbackExt)
	return fmt.Sprintf(
		"tenants/%d/articles/%d/images/%04d/%02d/%02d/%s.%s",
		tenantID,
		articleID,
		now.Year(),
		int(now.Month()),
		now.Day(),
		uuid.NewString(),
		extension,
	)
}

func normalizeArticleImageExtension(fileName string, fallbackExt string) string {
	extension := strings.TrimPrefix(strings.ToLower(filepath.Ext(strings.TrimSpace(fileName))), ".")
	if extension != "" {
		switch extension {
		case "jpg", "jpeg":
			return "jpg"
		case "png", "gif", "webp":
			return extension
		}
	}
	return fallbackExt
}

func resolveWordCount(markdown *string, stored int) int {
	if markdown != nil {
		if counted := countArticleWords(*markdown); counted > 0 {
			return counted
		}
	}
	return stored
}

func resolveArticleGenerationMode(sourceType string, inputParamsJSON []byte) *string {
	if sourceType != "custom_generation" {
		return nil
	}

	if len(inputParamsJSON) > 0 {
		var payload map[string]interface{}
		if err := json.Unmarshal(inputParamsJSON, &payload); err == nil {
			if mode := strings.TrimSpace(extractString(payload, "generation_mode")); mode != "" {
				return &mode
			}
		}
	}

	mode := "instant"
	return &mode
}

func nilIfEmptyString(value string) *string {
	value = strings.TrimSpace(value)
	if value == "" {
		return nil
	}
	return &value
}