package repository

import (
	"database/sql"
	"errors"
	"fmt"
	"strings"

	"github.com/wmms/wmms/internal/model"
	"github.com/wmms/wmms/pkg/database"
)

// ErrDuplicateMaterialCode 表示同组织下物料编码已被占用。
var ErrDuplicateMaterialCode = errors.New("物料编码已存在")

// BeginTx starts a new database transaction
func BeginTx() (*sql.Tx, error) {
	return database.DB.Begin()
}

// probeLimit 限制自动编码撞号后向后探测的次数：号段被大面积占用时宁可报错，
// 也不要让一次创建长时间空转。
const probeLimit = 1000

type MaterialRepo struct{}

func NewMaterialRepo() *MaterialRepo {
	return &MaterialRepo{}
}

func (r *MaterialRepo) IsActiveSubcategory(categoryID, organizationID int64) (bool, error) {
	query := `SELECT EXISTS(
		SELECT 1 FROM material_categories
		WHERE id = ? AND organization_id = ? AND parent_id IS NOT NULL AND status = 'active'
	)`
	var exists bool
	err := database.DB.QueryRow(query, categoryID, organizationID).Scan(&exists)
	return exists, err
}

// sqlExecer 让插入语句既能直接走连接池，也能跑在事务里。
type sqlExecer interface {
	Exec(query string, args ...interface{}) (sql.Result, error)
}

// insertMaterial 写入物料并回填自增主键，唯一键冲突统一翻译成
// ErrDuplicateMaterialCode。
func insertMaterial(execer sqlExecer, m *model.Material) error {
	query := `INSERT INTO materials (organization_id, material_code, name, material_image, spec, manufacturer_model, category_id, base_unit_id, unit, status, version) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`
	result, err := execer.Exec(query, m.OrganizationID, m.MaterialCode, m.Name, m.MaterialImage, m.Spec,
		m.ManufacturerModel, m.CategoryID, m.BaseUnitID, m.Unit, m.Status, m.Version)
	if err != nil {
		if strings.Contains(err.Error(), "Duplicate entry") {
			return ErrDuplicateMaterialCode
		}
		return err
	}
	id, err := result.LastInsertId()
	if err != nil {
		return err
	}
	m.ID = id
	return nil
}

// lockCodeRule 锁住小类当前启用的编码规则行，返回 nil 表示该小类没有规则。
// FOR UPDATE 让同一个小类的并发创建串行化，避免两条记录抢到同一个流水号。
func lockCodeRule(tx *sql.Tx, organizationID, categoryID int64) (*model.CodeRule, error) {
	query := `SELECT id, organization_id, category_id, prefix, sequence_length, next_sequence FROM code_rules WHERE organization_id = ? AND category_id = ? AND status = 'active' FOR UPDATE`
	rule := &model.CodeRule{}
	err := tx.QueryRow(query, organizationID, categoryID).Scan(&rule.ID, &rule.OrganizationID,
		&rule.CategoryID, &rule.Prefix, &rule.SequenceLength, &rule.NextSequence)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return rule, nil
}

// isMaterialCodeTaken 判断同组织下某个物料编码是否已被占用。
func isMaterialCodeTaken(tx *sql.Tx, organizationID int64, code string) (bool, error) {
	query := `SELECT EXISTS(SELECT 1 FROM materials WHERE organization_id = ? AND material_code = ?)`
	var exists bool
	err := tx.QueryRow(query, organizationID, code).Scan(&exists)
	return exists, err
}

// CreateWithCodeRule 在事务内插入物料，并根据提交的编码决定是否推进号段。
//
// 提交的编码是不是「规则当前的产物」决定了走哪条分支：相等说明这个编码来自自动
// 生成、用户没有改过，于是沿着号段向后探测出第一个没被占用的流水号，插入成功后
// 把 next_sequence 推进到它之后；不相等说明用户手改了编码、或者该小类根本没有
// 规则，此时原样插入、号段保持不变，撞唯一键就报编码已存在。
func (r *MaterialRepo) CreateWithCodeRule(m *model.Material, submittedCode string) error {
	tx, err := BeginTx()
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback() }()

	var categoryID int64
	if m.CategoryID != nil {
		categoryID = *m.CategoryID
	}
	rule, err := lockCodeRule(tx, m.OrganizationID, categoryID)
	if err != nil {
		return err
	}

	code := submittedCode
	var nextSequence int64
	if rule != nil && code == rule.FormatCode(rule.NextSequence) {
		sequence := rule.NextSequence
		for probed := 0; probed < probeLimit; probed++ {
			code = rule.FormatCode(sequence)
			taken, err := isMaterialCodeTaken(tx, m.OrganizationID, code)
			if err != nil {
				return err
			}
			if !taken {
				nextSequence = sequence + 1
				break
			}
			sequence++
		}
		if nextSequence == 0 {
			return fmt.Errorf("编码规则 %s 的可用流水号已用尽", rule.Prefix)
		}
	}

	m.MaterialCode = code
	if err := insertMaterial(tx, m); err != nil {
		return err
	}
	if nextSequence > 0 {
		if _, err := tx.Exec(`UPDATE code_rules SET next_sequence = ? WHERE id = ?`, nextSequence, rule.ID); err != nil {
			return err
		}
	}
	if err := tx.Commit(); err != nil {
		return err
	}
	return r.GetByID(m.ID, m)
}

func (r *MaterialRepo) GetByID(id int64, m *model.Material) error {
	query := `SELECT id, organization_id, material_code, name, material_image, spec, manufacturer_model,
		category_id, base_unit_id, unit, status, version, created_at, updated_at
		FROM materials WHERE id = ?`
	var materialImage sql.NullString
	var manufacturerModel sql.NullString
	err := database.DB.QueryRow(query, id).Scan(&m.ID, &m.OrganizationID, &m.MaterialCode, &m.Name, &materialImage,
		&m.Spec, &manufacturerModel, &m.CategoryID, &m.BaseUnitID,
		&m.Unit, &m.Status, &m.Version, &m.CreatedAt, &m.UpdatedAt)
	if err != nil {
		return err
	}
	if materialImage.Valid {
		m.MaterialImage = &materialImage.String
	}
	if manufacturerModel.Valid {
		m.ManufacturerModel = &manufacturerModel.String
	}
	return nil
}

func (r *MaterialRepo) GetByMaterialCode(code string) (*model.Material, error) {
	m := &model.Material{}
	query := `SELECT id, organization_id, material_code, name, material_image, spec, manufacturer_model,
		category_id, base_unit_id, unit, status, version, created_at, updated_at
		FROM materials WHERE material_code = ?`
	var materialImage sql.NullString
	var manufacturerModel sql.NullString
	err := database.DB.QueryRow(query, code).Scan(&m.ID, &m.OrganizationID, &m.MaterialCode, &m.Name, &materialImage,
		&m.Spec, &manufacturerModel, &m.CategoryID, &m.BaseUnitID,
		&m.Unit, &m.Status, &m.Version, &m.CreatedAt, &m.UpdatedAt)
	if err != nil {
		return nil, err
	}
	if materialImage.Valid {
		m.MaterialImage = &materialImage.String
	}
	if manufacturerModel.Valid {
		m.ManufacturerModel = &manufacturerModel.String
	}
	return m, nil
}

func (r *MaterialRepo) List(search, status string, limit, offset int) ([]model.Material, int64, error) {
	countQuery := `SELECT COUNT(*) FROM materials WHERE 1=1`
	var countArgs []interface{}
	if status != "all" {
		countQuery += ` AND status = ?`
		countArgs = append(countArgs, status)
	}

	if search != "" {
		countQuery += ` AND (material_code LIKE ? OR name LIKE ?)`
		searchPattern := "%" + search + "%"
		countArgs = append(countArgs, searchPattern, searchPattern)
	}

	var total int64
	err := database.DB.QueryRow(countQuery, countArgs...).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	query := `SELECT id, organization_id, material_code, name, material_image, spec, manufacturer_model,
		category_id, base_unit_id, unit, status, version, created_at, updated_at
		FROM materials WHERE 1=1`
	var args []interface{}
	if status != "all" {
		query += ` AND status = ?`
		args = append(args, status)
	}

	if search != "" {
		query += ` AND (material_code LIKE ? OR name LIKE ?)`
		searchPattern := "%" + search + "%"
		args = append(args, searchPattern, searchPattern)
	}
	query += ` ORDER BY id DESC LIMIT ? OFFSET ?`
	args = append(args, limit, offset)

	rows, err := database.DB.Query(query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var materials []model.Material
	for rows.Next() {
		var m model.Material
		var materialImage sql.NullString
		var manufacturerModel sql.NullString
		err := rows.Scan(&m.ID, &m.OrganizationID, &m.MaterialCode, &m.Name, &materialImage, &m.Spec,
			&manufacturerModel, &m.CategoryID, &m.BaseUnitID,
			&m.Unit, &m.Status, &m.Version, &m.CreatedAt, &m.UpdatedAt)
		if err != nil {
			return nil, 0, err
		}
		if materialImage.Valid {
			m.MaterialImage = &materialImage.String
		}
		if manufacturerModel.Valid {
			m.ManufacturerModel = &manufacturerModel.String
		}
		materials = append(materials, m)
	}
	return materials, total, nil
}

func (r *MaterialRepo) Update(id int64, req *model.UpdateMaterialRequest) error {
	var sets []string
	var args []interface{}

	if req.Name != "" {
		sets = append(sets, "name = ?")
		args = append(args, req.Name)
	}
	if req.MaterialImage != nil && *req.MaterialImage != "" {
		sets = append(sets, "material_image = ?")
		args = append(args, *req.MaterialImage)
	}
	if req.Spec != "" {
		sets = append(sets, "spec = ?")
		args = append(args, req.Spec)
	}
	if req.ManufacturerModel != nil && *req.ManufacturerModel != "" {
		sets = append(sets, "manufacturer_model = ?")
		args = append(args, *req.ManufacturerModel)
	}
	if req.CategoryID != nil {
		sets = append(sets, "category_id = ?")
		args = append(args, req.CategoryID)
	}
	if req.Unit != "" {
		sets = append(sets, "unit = ?")
		args = append(args, req.Unit)
	}
	if req.BaseUnitID != nil {
		sets = append(sets, "base_unit_id = ?")
		args = append(args, req.BaseUnitID)
	}
	if req.Status != "" {
		sets = append(sets, "status = ?")
		args = append(args, req.Status)
	}
	sets = append(sets, "version = version + 1")
	if len(sets) == 0 {
		return nil
	}

	query := fmt.Sprintf("UPDATE materials SET %s WHERE id = ?", strings.Join(sets, ", "))
	args = append(args, id)
	_, err := database.DB.Exec(query, args...)
	return err
}

func (r *MaterialRepo) Delete(id int64) error {
	// Check if material has related records
	var count int

	// Check inbound_items
	database.DB.QueryRow(`SELECT COUNT(*) FROM inbound_items WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有入库记录，无法删除")
	}

	// Check outbound_items
	database.DB.QueryRow(`SELECT COUNT(*) FROM outbound_items WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有出库记录，无法删除")
	}

	// Check stock_logs
	database.DB.QueryRow(`SELECT COUNT(*) FROM stock_logs WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有库存流水记录，无法删除")
	}

	_, err := database.DB.Exec(`DELETE FROM materials WHERE id = ?`, id)
	return err
}

func (r *MaterialRepo) Obsolete(id int64) error {
	var nonZero int
	if err := database.DB.QueryRow(`SELECT COUNT(*) FROM inventory_balances WHERE material_id = ? AND (on_hand <> 0 OR reserved <> 0 OR locked <> 0 OR in_transit <> 0)`, id).Scan(&nonZero); err != nil {
		return err
	}
	if nonZero > 0 {
		return fmt.Errorf("该物料仍有库存，无法作废")
	}
	result, err := database.DB.Exec(`UPDATE materials SET status = 'obsolete', version = version + 1 WHERE id = ?`, id)
	if err != nil {
		return err
	}
	// version always increments, so zero affected rows means the material does
	// not exist; re-obsoleting an already-obsolete material still reports 1.
	affected, _ := result.RowsAffected()
	if affected == 0 {
		return fmt.Errorf("物料不存在")
	}
	return nil
}

func (r *MaterialRepo) Restore(id int64) error {
	result, err := database.DB.Exec(`UPDATE materials SET status = 'active', version = version + 1 WHERE id = ?`, id)
	if err != nil {
		return err
	}
	affected, _ := result.RowsAffected()
	if affected == 0 {
		return fmt.Errorf("物料不存在")
	}
	return nil
}