package cassandradb

import (
	"context"
	"encoding/json"
	"fmt"
	"reflect"
	"strings"
	"time"

	"github.com/authorizerdev/authorizer/server/db/models"
	"github.com/authorizerdev/authorizer/server/graph/model"
	"github.com/gocql/gocql"
	"github.com/google/uuid"
)

// AddEmailTemplate to add EmailTemplate
func (p *provider) AddEmailTemplate(ctx context.Context, emailTemplate models.EmailTemplate) (*model.EmailTemplate, error) {
	if emailTemplate.ID == "" {
		emailTemplate.ID = uuid.New().String()
	}

	emailTemplate.Key = emailTemplate.ID
	emailTemplate.CreatedAt = time.Now().Unix()
	emailTemplate.UpdatedAt = time.Now().Unix()

	existingEmailTemplate, _ := p.GetEmailTemplateByEventName(ctx, emailTemplate.EventName)
	if existingEmailTemplate != nil {
		return nil, fmt.Errorf("Email template with %s event_name already exists", emailTemplate.EventName)
	}

	insertQuery := fmt.Sprintf("INSERT INTO %s (id, event_name, template,  created_at, updated_at) VALUES ('%s', '%s', '%s', %d, %d)", KeySpace+"."+models.Collections.EmailTemplate, emailTemplate.ID, emailTemplate.EventName, emailTemplate.Template, emailTemplate.CreatedAt, emailTemplate.UpdatedAt)
	err := p.db.Query(insertQuery).Exec()
	if err != nil {
		return nil, err
	}

	return emailTemplate.AsAPIEmailTemplate(), nil
}

// UpdateEmailTemplate to update EmailTemplate
func (p *provider) UpdateEmailTemplate(ctx context.Context, emailTemplate models.EmailTemplate) (*model.EmailTemplate, error) {
	emailTemplate.UpdatedAt = time.Now().Unix()

	bytes, err := json.Marshal(emailTemplate)
	if err != nil {
		return nil, err
	}
	// use decoder instead of json.Unmarshall, because it converts int64 -> float64 after unmarshalling
	decoder := json.NewDecoder(strings.NewReader(string(bytes)))
	decoder.UseNumber()
	emailTemplateMap := map[string]interface{}{}
	err = decoder.Decode(&emailTemplateMap)
	if err != nil {
		return nil, err
	}

	updateFields := ""
	for key, value := range emailTemplateMap {
		if key == "_id" {
			continue
		}

		if key == "_key" {
			continue
		}

		if value == nil {
			updateFields += fmt.Sprintf("%s = null,", key)
			continue
		}

		valueType := reflect.TypeOf(value)
		if valueType.Name() == "string" {
			updateFields += fmt.Sprintf("%s = '%s', ", key, value.(string))
		} else {
			updateFields += fmt.Sprintf("%s = %v, ", key, value)
		}
	}
	updateFields = strings.Trim(updateFields, " ")
	updateFields = strings.TrimSuffix(updateFields, ",")

	query := fmt.Sprintf("UPDATE %s SET %s WHERE id = '%s'", KeySpace+"."+models.Collections.EmailTemplate, updateFields, emailTemplate.ID)
	err = p.db.Query(query).Exec()
	if err != nil {
		return nil, err
	}

	return emailTemplate.AsAPIEmailTemplate(), nil
}

// ListEmailTemplates to list EmailTemplate
func (p *provider) ListEmailTemplate(ctx context.Context, pagination model.Pagination) (*model.EmailTemplates, error) {
	emailTemplates := []*model.EmailTemplate{}
	paginationClone := pagination

	totalCountQuery := fmt.Sprintf(`SELECT COUNT(*) FROM %s`, KeySpace+"."+models.Collections.EmailTemplate)
	err := p.db.Query(totalCountQuery).Consistency(gocql.One).Scan(&paginationClone.Total)
	if err != nil {
		return nil, err
	}

	// there is no offset in cassandra
	// so we fetch till limit + offset
	// and return the results from offset to limit
	query := fmt.Sprintf("SELECT id, event_name, template, created_at, updated_at FROM %s LIMIT %d", KeySpace+"."+models.Collections.EmailTemplate, pagination.Limit+pagination.Offset)

	scanner := p.db.Query(query).Iter().Scanner()
	counter := int64(0)
	for scanner.Next() {
		if counter >= pagination.Offset {
			var emailTemplate models.EmailTemplate
			err := scanner.Scan(&emailTemplate.ID, &emailTemplate.EventName, &emailTemplate.Template, &emailTemplate.CreatedAt, &emailTemplate.UpdatedAt)
			if err != nil {
				return nil, err
			}
			emailTemplates = append(emailTemplates, emailTemplate.AsAPIEmailTemplate())
		}
		counter++
	}

	return &model.EmailTemplates{
		Pagination:     &paginationClone,
		EmailTemplates: emailTemplates,
	}, nil
}

// GetEmailTemplateByID to get EmailTemplate by id
func (p *provider) GetEmailTemplateByID(ctx context.Context, emailTemplateID string) (*model.EmailTemplate, error) {
	var emailTemplate models.EmailTemplate
	query := fmt.Sprintf(`SELECT id, event_name, template, created_at, updated_at FROM %s WHERE id = '%s' LIMIT 1`, KeySpace+"."+models.Collections.EmailTemplate, emailTemplateID)
	err := p.db.Query(query).Consistency(gocql.One).Scan(&emailTemplate.ID, &emailTemplate.EventName, &emailTemplate.Template, &emailTemplate.CreatedAt, &emailTemplate.UpdatedAt)
	if err != nil {
		return nil, err
	}
	return emailTemplate.AsAPIEmailTemplate(), nil
}

// GetEmailTemplateByEventName to get EmailTemplate by event_name
func (p *provider) GetEmailTemplateByEventName(ctx context.Context, eventName string) (*model.EmailTemplate, error) {
	var emailTemplate models.EmailTemplate
	query := fmt.Sprintf(`SELECT id, event_name, template, created_at, updated_at FROM %s WHERE event_name = '%s' LIMIT 1 ALLOW FILTERING`, KeySpace+"."+models.Collections.EmailTemplate, eventName)
	err := p.db.Query(query).Consistency(gocql.One).Scan(&emailTemplate.ID, &emailTemplate.EventName, &emailTemplate.Template, &emailTemplate.CreatedAt, &emailTemplate.UpdatedAt)
	if err != nil {
		return nil, err
	}
	return emailTemplate.AsAPIEmailTemplate(), nil
}

// DeleteEmailTemplate to delete EmailTemplate
func (p *provider) DeleteEmailTemplate(ctx context.Context, emailTemplate *model.EmailTemplate) error {
	query := fmt.Sprintf("DELETE FROM %s WHERE id = '%s'", KeySpace+"."+models.Collections.EmailTemplate, emailTemplate.ID)
	err := p.db.Query(query).Exec()
	if err != nil {
		return err
	}

	return nil
}