package database

import (
	"context"
	"fmt"
	"regexp"
	"strings"

	"modelRT/common"
	"modelRT/constants"
	"modelRT/model"
	"modelRT/orm"
	modelsql "modelRT/sql"

	"gorm.io/gorm"
)

var parameterTableNamePattern = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)

// ParameterDataObject contains the resolved metadata needed to query a
// parameter attribute after its token has passed hierarchy validation.
type ParameterDataObject struct {
	Component      orm.Component
	Project        orm.ProjectManager
	TableName      string
	AttributeGroup string
	AttributeName  string
	AttributeType  string
}

// QueryParameterByDataObjectToken validates a four-part or seven-part
// parameter token. The component group resolves directly to the component
// table; other groups resolve through project_manager and a dynamic table.
func QueryParameterByDataObjectToken(ctx context.Context, db *gorm.DB, token string) (*ParameterDataObject, error) {
	componentQuery, componentArgs, parts, err := buildParameterComponentQuery(token)
	if err != nil {
		return nil, err
	}

	var components []orm.Component
	if err := db.WithContext(ctx).Raw(componentQuery, componentArgs...).Scan(&components).Error; err != nil {
		return nil, fmt.Errorf("query component for parameter token %q: %w", token, err)
	}

	switch len(components) {
	case 0:
		return nil, fmt.Errorf("%w: component hierarchy for %q", common.ErrParameterTokenNotFound, token)
	case 1:
		// Continue by resolving the component model and attribute group.
	default:
		return nil, fmt.Errorf("%w: component hierarchy for %q matched more than one record", common.ErrAmbiguousParameterToken, token)
	}

	attributeGroup := parts[len(parts)-2]
	attributeName := parts[len(parts)-1]
	component := components[0]
	if attributeGroup == "component" {
		attributeType, err := queryParameterAttributeType(ctx, db, "component", attributeName, token)
		if err != nil {
			return nil, err
		}
		return &ParameterDataObject{
			Component:      component,
			TableName:      "component",
			AttributeGroup: attributeGroup,
			AttributeName:  attributeName,
			AttributeType:  attributeType,
		}, nil
	}

	var projects []orm.ProjectManager
	if err := db.WithContext(ctx).
		Where("tag = ? AND group_name = ?", component.ModelName, attributeGroup).
		Limit(2).
		Find(&projects).Error; err != nil {
		return nil, fmt.Errorf("query project mapping for parameter token %q: %w", token, err)
	}

	switch len(projects) {
	case 0:
		return nil, fmt.Errorf("%w: model %q does not define attribute group %q", common.ErrParameterTokenNotFound, component.ModelName, attributeGroup)
	case 1:
		// Continue by validating the dynamic table and attribute.
	default:
		return nil, fmt.Errorf("%w: model %q and attribute group %q matched more than one project", common.ErrAmbiguousParameterToken, component.ModelName, attributeGroup)
	}

	project := projects[0]
	if !parameterTableNamePattern.MatchString(project.Name) {
		return nil, fmt.Errorf("project mapping for parameter token %q contains invalid table name %q", token, project.Name)
	}
	attributeType, err := queryParameterAttributeType(ctx, db, project.Name, attributeName, token)
	if err != nil {
		return nil, err
	}

	var recordCount int64
	if err := db.WithContext(ctx).
		Table(project.Name).
		Where("global_uuid = ? AND attribute_group = ?", component.GlobalUUID, attributeGroup).
		Count(&recordCount).Error; err != nil {
		return nil, fmt.Errorf("query dynamic record for parameter token %q: %w", token, err)
	}

	switch {
	case recordCount == 0:
		return nil, fmt.Errorf("%w: component %q has no %q parameter record", common.ErrParameterTokenNotFound, component.Tag, attributeGroup)
	case recordCount > 1:
		return nil, fmt.Errorf("%w: component %q has %d %q parameter records", common.ErrAmbiguousParameterToken, component.Tag, recordCount, attributeGroup)
	}

	return &ParameterDataObject{
		Component:      component,
		Project:        project,
		TableName:      project.Name,
		AttributeGroup: attributeGroup,
		AttributeName:  attributeName,
		AttributeType:  attributeType,
	}, nil
}

// QueryParameterDataObjectValue returns token7 from the component row or from
// a dynamic parameter row identified during token validation.
func QueryParameterDataObjectValue(ctx context.Context, db *gorm.DB, parameter *ParameterDataObject) (any, error) {
	if parameter == nil {
		return nil, fmt.Errorf("parameter data object is nil")
	}

	var record map[string]any
	query := db.WithContext(ctx).Table(parameter.TableName)
	if parameter.AttributeGroup == "component" {
		query = query.Where("tag = ?", parameter.Component.Tag)
	} else {
		query = query.Where("global_uuid = ? AND attribute_group = ?", parameter.Component.GlobalUUID, parameter.AttributeGroup)
	}
	result := query.Take(&record)
	if result.Error != nil {
		return nil, fmt.Errorf("query parameter value from table %q: %w", parameter.TableName, result.Error)
	}

	value, ok := record[parameter.AttributeName]
	if !ok {
		return nil, fmt.Errorf("parameter column %q is missing from table %q result", parameter.AttributeName, parameter.TableName)
	}
	return value, nil
}

// QueryParameterAttributeDescription returns the display name registered for
// token7 in basic.attribute.
func QueryParameterAttributeDescription(ctx context.Context, db *gorm.DB, attributeName string) (string, error) {
	var rows []struct {
		Description string `gorm:"column:attribute_name"`
	}
	if err := db.WithContext(ctx).
		Raw(modelsql.ParameterAttributeDescription, attributeName).
		Scan(&rows).Error; err != nil {
		return "", fmt.Errorf("query parameter description for attribute %q: %w", attributeName, err)
	}

	switch len(rows) {
	case 0:
		return "", fmt.Errorf("parameter description not found for attribute %q", attributeName)
	case 1:
		return rows[0].Description, nil
	default:
		return "", fmt.Errorf("ambiguous parameter description for attribute %q", attributeName)
	}
}

func queryParameterAttributeType(ctx context.Context, db *gorm.DB, tableName, attributeName, token string) (string, error) {
	var attributeType string
	result := db.WithContext(ctx).
		Raw(modelsql.ParameterAttributeColumnType, tableName, attributeName).
		Scan(&attributeType)
	if result.Error != nil {
		return "", fmt.Errorf("validate attribute column for parameter token %q: %w", token, result.Error)
	}
	if result.RowsAffected == 0 || attributeType == "" {
		return "", fmt.Errorf("%w: column %q does not exist in parameter table %q", common.ErrParameterTokenNotFound, attributeName, tableName)
	}
	return strings.ToUpper(attributeType), nil
}

func buildParameterComponentQuery(token string) (string, []any, []string, error) {
	dataObjectType, err := model.ClassifyDataObjectToken(token)
	if err != nil {
		return "", nil, nil, fmt.Errorf("%w %q: %v", common.ErrInvalidParameterToken, token, err)
	}
	if dataObjectType != constants.DataObjectTypeParameter {
		return "", nil, nil, fmt.Errorf("%w %q: token does not identify a parameter", common.ErrInvalidParameterToken, token)
	}

	parts := strings.Split(token, ".")
	var where string
	var args []any
	switch len(parts) {
	case 7:
		where = modelsql.ParameterSevenPartTokenWhere
		args = []any{parts[0], parts[1], parts[2], parts[3], parts[4]}
	case 4:
		where = modelsql.ParameterFourPartTokenWhere
		args = []any{parts[0], parts[1]}
	default:
		return "", nil, nil, fmt.Errorf("%w %q: expected 4 or 7 segments", common.ErrInvalidParameterToken, token)
	}

	query := compactParameterSQL(strings.Join([]string{
		modelsql.ParameterComponentQueryBase,
		where,
		modelsql.ParameterLimitTwo,
	}, "\n"))
	return query, args, parts, nil
}

func compactParameterSQL(statement string) string {
	return strings.Join(strings.Fields(statement), " ")
}