package db

import (
	"tercul/internal/observability"
	"time"

	"gorm.io/gorm"
)

const (
	callBackBeforeName = "prometheus:before"
	callBackAfterName  = "prometheus:after"
	startTime          = "start_time"
)

type PrometheusPlugin struct {
	Metrics *observability.Metrics
}

func (p *PrometheusPlugin) Name() string {
	return "PrometheusPlugin"
}

func (p *PrometheusPlugin) Initialize(db *gorm.DB) error {
	// Before callbacks
	db.Callback().Create().Before("gorm:create").Register(callBackBeforeName, p.before)
	db.Callback().Query().Before("gorm:query").Register(callBackBeforeName, p.before)
	db.Callback().Update().Before("gorm:update").Register(callBackBeforeName, p.before)
	db.Callback().Delete().Before("gorm:delete").Register(callBackBeforeName, p.before)
	db.Callback().Row().Before("gorm:row").Register(callBackBeforeName, p.before)
	db.Callback().Raw().Before("gorm:raw").Register(callBackBeforeName, p.before)

	// After callbacks
	db.Callback().Create().After("gorm:create").Register(callBackAfterName, p.after)
	db.Callback().Query().After("gorm:query").Register(callBackAfterName, p.after)
	db.Callback().Update().After("gorm:update").Register(callBackAfterName, p.after)
	db.Callback().Delete().After("gorm:delete").Register(callBackAfterName, p.after)
	db.Callback().Row().After("gorm:row").Register(callBackAfterName, p.after)
	db.Callback().Raw().After("gorm:raw").Register(callBackAfterName, p.after)

	return nil
}

func (p *PrometheusPlugin) before(db *gorm.DB) {
	db.Set(startTime, time.Now())
}

func (p *PrometheusPlugin) after(db *gorm.DB) {
	_ts, ok := db.Get(startTime)
	if !ok {
		return
	}

	ts, ok := _ts.(time.Time)
	if !ok {
		return
	}

	operation := db.Statement.SQL.String()
	if len(operation) > 50 { // Truncate long queries
		operation = operation[:50]
	}

	status := "success"
	if db.Error != nil {
		status = "error"
	}

	duration := time.Since(ts).Seconds()
	p.Metrics.DBQueryDuration.WithLabelValues(operation, status).Observe(duration)
	p.Metrics.DBQueriesTotal.WithLabelValues(operation, status).Inc()
}

func NewPrometheusPlugin(metrics *observability.Metrics) *PrometheusPlugin {
	return &PrometheusPlugin{Metrics: metrics}
}