package app

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"strings"

	"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/middleware"
	"github.com/geo-platform/tenant-api/internal/shared/response"
)

type BrandService struct {
	pool      *pgxpool.Pool
	auditLogs *auditlog.AsyncWriter
}

func NewBrandService(pool *pgxpool.Pool, auditLogs *auditlog.AsyncWriter) *BrandService {
	return &BrandService{pool: pool, auditLogs: auditLogs}
}

// --- Brand CRUD ---

type BrandRequest struct {
	Name        string  `json:"name" binding:"required"`
	Website     *string `json:"website"`
	Description *string `json:"description"`
}

type BrandResponse struct {
	ID          int64   `json:"id"`
	Name        string  `json:"name"`
	Website     *string `json:"website"`
	Description *string `json:"description"`
	Status      string  `json:"status"`
	CreatedAt   string  `json:"created_at"`
	UpdatedAt   string  `json:"updated_at"`
}

func (s *BrandService) List(ctx context.Context) ([]BrandResponse, error) {
	actor := auth.MustActor(ctx)
	rows, err := s.pool.Query(ctx, `
		SELECT id, name, website, description, status, created_at, updated_at
		FROM brands WHERE tenant_id = $1 AND deleted_at IS NULL ORDER BY created_at DESC
	`, actor.TenantID)
	if err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to list brands")
	}
	defer rows.Close()

	var brands []BrandResponse
	for rows.Next() {
		var b BrandResponse
		var ca, ua interface{}
		if err := rows.Scan(&b.ID, &b.Name, &b.Website, &b.Description, &b.Status, &ca, &ua); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		b.CreatedAt = fmt.Sprintf("%v", ca)
		b.UpdatedAt = fmt.Sprintf("%v", ua)
		brands = append(brands, b)
	}
	if brands == nil {
		brands = []BrandResponse{}
	}
	return brands, nil
}

func (s *BrandService) Create(ctx context.Context, req BrandRequest) (*BrandResponse, error) {
	actor := auth.MustActor(ctx)
	normalizeBrandRequest(&req)
	if req.Name == "" {
		return nil, response.ErrBadRequest(40001, "invalid_params", "name is required")
	}
	var id int64
	var ca interface{}
	err := s.pool.QueryRow(ctx, `
		INSERT INTO brands (tenant_id, name, website, description, status)
		VALUES ($1, $2, $3, $4, 'active') RETURNING id, created_at
	`, actor.TenantID, req.Name, req.Website, req.Description).Scan(&id, &ca)
	if err != nil {
		return nil, response.ErrConflict(40901, "brand_exists", "brand with this name already exists")
	}

	afterJSON, _ := json.Marshal(map[string]interface{}{"id": id, "name": req.Name})
	result := "success"
	resourceType := "brand"
	requestID := middleware.RequestIDFromContext(ctx)
	s.auditLogs.Log(auditlog.Entry{
		OperatorID:   actor.UserID,
		TenantID:     &actor.TenantID,
		Module:       "brand",
		Action:       "create",
		ResourceType: &resourceType,
		ResourceID:   &id,
		RequestID:    nilIfEmptyString(requestID),
		AfterJSON:    afterJSON,
		Result:       &result,
	})

	return &BrandResponse{
		ID:          id,
		Name:        req.Name,
		Website:     req.Website,
		Description: req.Description,
		Status:      "active",
		CreatedAt:   fmt.Sprintf("%v", ca),
	}, nil
}

func (s *BrandService) Detail(ctx context.Context, id int64) (*BrandResponse, error) {
	actor := auth.MustActor(ctx)
	var b BrandResponse
	var ca, ua interface{}
	err := s.pool.QueryRow(ctx, `
		SELECT id, name, website, description, status, created_at, updated_at
		FROM brands WHERE id = $1 AND tenant_id = $2 AND deleted_at IS NULL
	`, id, actor.TenantID).Scan(&b.ID, &b.Name, &b.Website, &b.Description, &b.Status, &ca, &ua)
	if err != nil {
		return nil, response.ErrNotFound(40420, "brand_not_found", "brand not found")
	}
	b.CreatedAt = fmt.Sprintf("%v", ca)
	b.UpdatedAt = fmt.Sprintf("%v", ua)
	return &b, nil
}

func (s *BrandService) Update(ctx context.Context, id int64, req BrandRequest) error {
	actor := auth.MustActor(ctx)
	normalizeBrandRequest(&req)
	if req.Name == "" {
		return response.ErrBadRequest(40001, "invalid_params", "name is required")
	}
	tag, err := s.pool.Exec(ctx, `
		UPDATE brands SET name = $1, website = $2, description = $3, updated_at = NOW()
		WHERE id = $4 AND tenant_id = $5 AND deleted_at IS NULL
	`, req.Name, req.Website, req.Description, id, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40420, "brand_not_found", "brand not found")
	}
	return nil
}

func normalizeBrandRequest(req *BrandRequest) {
	req.Name = strings.TrimSpace(req.Name)
	req.Website = normalizeOptionalString(req.Website)
	req.Description = normalizeOptionalString(req.Description)
}

func normalizeOptionalString(value *string) *string {
	if value == nil {
		return nil
	}
	return nilIfEmptyString(*value)
}

func (s *BrandService) Delete(ctx context.Context, id int64) error {
	actor := auth.MustActor(ctx)
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	tag, err := tx.Exec(ctx, `UPDATE brands 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(40420, "brand_not_found", "brand not found")
	}
	_, _ = tx.Exec(ctx, `UPDATE brand_keywords SET deleted_at = NOW(), updated_at = NOW() WHERE brand_id = $1 AND tenant_id = $2 AND deleted_at IS NULL`, id, actor.TenantID)
	_, _ = tx.Exec(ctx, `UPDATE brand_questions SET deleted_at = NOW(), updated_at = NOW() WHERE brand_id = $1 AND tenant_id = $2 AND deleted_at IS NULL`, id, actor.TenantID)
	_, _ = tx.Exec(ctx, `UPDATE competitors SET deleted_at = NOW(), updated_at = NOW() WHERE brand_id = $1 AND tenant_id = $2 AND deleted_at IS NULL`, id, actor.TenantID)

	afterJSON, _ := json.Marshal(map[string]interface{}{"id": id, "action": "cascade_soft_delete"})
	if err := tx.Commit(ctx); err != nil {
		return err
	}

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

	return nil
}

// --- Keyword CRUD ---

type KeywordRequest struct {
	Name string `json:"name" binding:"required"`
}

type KeywordResponse struct {
	ID        int64  `json:"id"`
	BrandID   int64  `json:"brand_id"`
	Name      string `json:"name"`
	Status    string `json:"status"`
	CreatedAt string `json:"created_at"`
}

func (s *BrandService) ListKeywords(ctx context.Context, brandID int64) ([]KeywordResponse, error) {
	actor := auth.MustActor(ctx)
	rows, err := s.pool.Query(ctx, `
		SELECT id, brand_id, name, status, created_at FROM brand_keywords
		WHERE brand_id = $1 AND tenant_id = $2 AND deleted_at IS NULL ORDER BY created_at DESC
	`, brandID, actor.TenantID)
	if err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to list keywords")
	}
	defer rows.Close()

	var keywords []KeywordResponse
	for rows.Next() {
		var k KeywordResponse
		var ca interface{}
		if err := rows.Scan(&k.ID, &k.BrandID, &k.Name, &k.Status, &ca); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		k.CreatedAt = fmt.Sprintf("%v", ca)
		keywords = append(keywords, k)
	}
	if keywords == nil {
		keywords = []KeywordResponse{}
	}
	return keywords, nil
}

func (s *BrandService) CreateKeyword(ctx context.Context, brandID int64, req KeywordRequest) (*KeywordResponse, error) {
	actor := auth.MustActor(ctx)
	var id int64
	var ca interface{}
	err := s.pool.QueryRow(ctx, `
		INSERT INTO brand_keywords (tenant_id, brand_id, name, status) VALUES ($1, $2, $3, 'active') RETURNING id, created_at
	`, actor.TenantID, brandID, req.Name).Scan(&id, &ca)
	if err != nil {
		return nil, response.ErrConflict(40902, "keyword_exists", "keyword with this name already exists for this brand")
	}
	return &KeywordResponse{ID: id, BrandID: brandID, Name: req.Name, Status: "active", CreatedAt: fmt.Sprintf("%v", ca)}, nil
}

func (s *BrandService) UpdateKeyword(ctx context.Context, brandID, keywordID int64, req KeywordRequest) error {
	actor := auth.MustActor(ctx)
	tag, err := s.pool.Exec(ctx, `
		UPDATE brand_keywords SET name = $1, updated_at = NOW()
		WHERE id = $2 AND brand_id = $3 AND tenant_id = $4 AND deleted_at IS NULL
	`, req.Name, keywordID, brandID, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40421, "keyword_not_found", "keyword not found")
	}
	return nil
}

func (s *BrandService) DeleteKeyword(ctx context.Context, brandID, keywordID int64) error {
	actor := auth.MustActor(ctx)
	tag, err := s.pool.Exec(ctx, `
		UPDATE brand_keywords SET deleted_at = NOW(), updated_at = NOW()
		WHERE id = $1 AND brand_id = $2 AND tenant_id = $3 AND deleted_at IS NULL
	`, keywordID, brandID, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40421, "keyword_not_found", "keyword not found")
	}
	return nil
}

// --- Question CRUD with versioning ---

type QuestionRequest struct {
	KeywordID    int64  `json:"keyword_id" binding:"required"`
	QuestionText string `json:"question_text" binding:"required"`
}

type QuestionResponse struct {
	ID               int64   `json:"id"`
	BrandID          int64   `json:"brand_id"`
	KeywordID        int64   `json:"keyword_id"`
	CurrentVersionID *int64  `json:"current_version_id"`
	QuestionText     *string `json:"question_text"`
	VersionNo        *int    `json:"version_no"`
	Status           string  `json:"status"`
	CreatedAt        string  `json:"created_at"`
}

func (s *BrandService) ListQuestions(ctx context.Context, brandID int64, keywordID *int64) ([]QuestionResponse, error) {
	actor := auth.MustActor(ctx)
	query := `
		SELECT q.id, q.brand_id, q.keyword_id, q.current_version_id, q.status, q.created_at,
		       v.question_text, v.version_no
		FROM brand_questions q
		LEFT JOIN brand_question_versions v ON v.id = q.current_version_id
		WHERE q.brand_id = $1 AND q.tenant_id = $2 AND q.deleted_at IS NULL`
	args := []interface{}{brandID, actor.TenantID}

	if keywordID != nil {
		query += ` AND q.keyword_id = $3`
		args = append(args, *keywordID)
	}
	query += ` ORDER BY q.created_at DESC`

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

	var questions []QuestionResponse
	for rows.Next() {
		var q QuestionResponse
		var ca interface{}
		if err := rows.Scan(&q.ID, &q.BrandID, &q.KeywordID, &q.CurrentVersionID, &q.Status, &ca, &q.QuestionText, &q.VersionNo); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		q.CreatedAt = fmt.Sprintf("%v", ca)
		questions = append(questions, q)
	}
	if questions == nil {
		questions = []QuestionResponse{}
	}
	return questions, nil
}

func (s *BrandService) CreateQuestion(ctx context.Context, brandID int64, req QuestionRequest) (*QuestionResponse, error) {
	actor := auth.MustActor(ctx)
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, fmt.Errorf("begin tx: %w", err)
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	var questionID int64
	err = tx.QueryRow(ctx, `
		INSERT INTO brand_questions (tenant_id, brand_id, keyword_id, status) VALUES ($1, $2, $3, 'active') RETURNING id
	`, actor.TenantID, brandID, req.KeywordID).Scan(&questionID)
	if err != nil {
		return nil, response.ErrInternal(50010, "create_failed", "failed to create question")
	}

	hash := fmt.Sprintf("%x", sha256.Sum256([]byte(req.QuestionText)))
	var versionID int64
	err = tx.QueryRow(ctx, `
		INSERT INTO brand_question_versions (question_id, question_text, question_hash, version_no, is_active)
		VALUES ($1, $2, $3, 1, true) RETURNING id
	`, questionID, req.QuestionText, hash).Scan(&versionID)
	if err != nil {
		return nil, response.ErrInternal(50010, "create_version_failed", "failed to create question version")
	}

	_, _ = tx.Exec(ctx, `UPDATE brand_questions SET current_version_id = $1 WHERE id = $2`, versionID, questionID)

	if err := tx.Commit(ctx); err != nil {
		return nil, fmt.Errorf("commit: %w", err)
	}

	vno := 1
	return &QuestionResponse{
		ID: questionID, BrandID: brandID, KeywordID: req.KeywordID,
		CurrentVersionID: &versionID, QuestionText: &req.QuestionText, VersionNo: &vno, Status: "active",
	}, nil
}

type UpdateQuestionRequest struct {
	QuestionText string `json:"question_text" binding:"required"`
}

func (s *BrandService) UpdateQuestion(ctx context.Context, brandID, questionID int64, req UpdateQuestionRequest) error {
	actor := auth.MustActor(ctx)
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer func() {
		_ = tx.Rollback(ctx)
	}()

	// Verify ownership
	var exists bool
	_ = tx.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM brand_questions WHERE id = $1 AND brand_id = $2 AND tenant_id = $3 AND deleted_at IS NULL)`,
		questionID, brandID, actor.TenantID).Scan(&exists)
	if !exists {
		return response.ErrNotFound(40422, "question_not_found", "question not found")
	}

	// Deactivate current version
	_, _ = tx.Exec(ctx, `UPDATE brand_question_versions SET is_active = false WHERE question_id = $1 AND is_active = true`, questionID)

	// Get next version number
	var maxVersion int
	_ = tx.QueryRow(ctx, `SELECT COALESCE(MAX(version_no), 0) FROM brand_question_versions WHERE question_id = $1`, questionID).Scan(&maxVersion)

	hash := fmt.Sprintf("%x", sha256.Sum256([]byte(req.QuestionText)))
	var versionID int64
	err = tx.QueryRow(ctx, `
		INSERT INTO brand_question_versions (question_id, question_text, question_hash, version_no, is_active)
		VALUES ($1, $2, $3, $4, true) RETURNING id
	`, questionID, req.QuestionText, hash, maxVersion+1).Scan(&versionID)
	if err != nil {
		return fmt.Errorf("create version: %w", err)
	}

	_, _ = tx.Exec(ctx, `UPDATE brand_questions SET current_version_id = $1, updated_at = NOW() WHERE id = $2`, versionID, questionID)

	return tx.Commit(ctx)
}

func (s *BrandService) DeleteQuestion(ctx context.Context, brandID, questionID int64) error {
	actor := auth.MustActor(ctx)
	tag, err := s.pool.Exec(ctx, `
		UPDATE brand_questions SET deleted_at = NOW(), updated_at = NOW()
		WHERE id = $1 AND brand_id = $2 AND tenant_id = $3 AND deleted_at IS NULL
	`, questionID, brandID, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40422, "question_not_found", "question not found")
	}
	return nil
}

// --- Competitor CRUD ---

type CompetitorRequest struct {
	Name             string           `json:"name" binding:"required"`
	Website          *string          `json:"website"`
	Description      *string          `json:"description"`
	ProductLinesJSON *json.RawMessage `json:"product_lines_json"`
}

type CompetitorResponse struct {
	ID               int64            `json:"id"`
	BrandID          int64            `json:"brand_id"`
	Name             string           `json:"name"`
	Website          *string          `json:"website"`
	Description      *string          `json:"description"`
	ProductLinesJSON *json.RawMessage `json:"product_lines_json"`
	CreatedAt        string           `json:"created_at"`
}

func (s *BrandService) ListCompetitors(ctx context.Context, brandID int64) ([]CompetitorResponse, error) {
	actor := auth.MustActor(ctx)
	rows, err := s.pool.Query(ctx, `
		SELECT id, brand_id, name, website, description, product_lines_json, created_at
		FROM competitors WHERE brand_id = $1 AND tenant_id = $2 AND deleted_at IS NULL ORDER BY created_at DESC
	`, brandID, actor.TenantID)
	if err != nil {
		return nil, response.ErrInternal(50010, "query_failed", "failed to list competitors")
	}
	defer rows.Close()

	var comps []CompetitorResponse
	for rows.Next() {
		var c CompetitorResponse
		var ca interface{}
		var plJSON []byte
		if err := rows.Scan(&c.ID, &c.BrandID, &c.Name, &c.Website, &c.Description, &plJSON, &ca); err != nil {
			return nil, response.ErrInternal(50010, "scan_failed", err.Error())
		}
		c.CreatedAt = fmt.Sprintf("%v", ca)
		if plJSON != nil {
			raw := json.RawMessage(plJSON)
			c.ProductLinesJSON = &raw
		}
		comps = append(comps, c)
	}
	if comps == nil {
		comps = []CompetitorResponse{}
	}
	return comps, nil
}

func (s *BrandService) CreateCompetitor(ctx context.Context, brandID int64, req CompetitorRequest) (*CompetitorResponse, error) {
	actor := auth.MustActor(ctx)
	var plJSON []byte
	if req.ProductLinesJSON != nil {
		plJSON = *req.ProductLinesJSON
	}

	var id int64
	var ca interface{}
	err := s.pool.QueryRow(ctx, `
		INSERT INTO competitors (tenant_id, brand_id, name, website, description, product_lines_json)
		VALUES ($1, $2, $3, $4, $5, $6) RETURNING id, created_at
	`, actor.TenantID, brandID, req.Name, req.Website, req.Description, plJSON).Scan(&id, &ca)
	if err != nil {
		return nil, response.ErrInternal(50010, "create_failed", "failed to create competitor")
	}
	return &CompetitorResponse{ID: id, BrandID: brandID, Name: req.Name, Website: req.Website, Description: req.Description, ProductLinesJSON: req.ProductLinesJSON, CreatedAt: fmt.Sprintf("%v", ca)}, nil
}

func (s *BrandService) UpdateCompetitor(ctx context.Context, brandID, competitorID int64, req CompetitorRequest) error {
	actor := auth.MustActor(ctx)
	var plJSON []byte
	if req.ProductLinesJSON != nil {
		plJSON = *req.ProductLinesJSON
	}
	tag, err := s.pool.Exec(ctx, `
		UPDATE competitors SET name = $1, website = $2, description = $3, product_lines_json = $4, updated_at = NOW()
		WHERE id = $5 AND brand_id = $6 AND tenant_id = $7 AND deleted_at IS NULL
	`, req.Name, req.Website, req.Description, plJSON, competitorID, brandID, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40423, "competitor_not_found", "competitor not found")
	}
	return nil
}

func (s *BrandService) DeleteCompetitor(ctx context.Context, brandID, competitorID int64) error {
	actor := auth.MustActor(ctx)
	tag, err := s.pool.Exec(ctx, `
		UPDATE competitors SET deleted_at = NOW(), updated_at = NOW()
		WHERE id = $1 AND brand_id = $2 AND tenant_id = $3 AND deleted_at IS NULL
	`, competitorID, brandID, actor.TenantID)
	if err != nil || tag.RowsAffected() == 0 {
		return response.ErrNotFound(40423, "competitor_not_found", "competitor not found")
	}
	return nil
}