package ocr

import (
	"fmt"

	"github.com/otiai10/gosseract/v2"
)

// Engine holds a pool of reusable Tesseract clients.
type Engine struct {
	pool    chan *gosseract.Client
	clients []*gosseract.Client
	lang    string
}

// NewEngine warms up poolSize Tesseract clients for the given language.
func NewEngine(lang string, poolSize int) (*Engine, error) {
	if poolSize < 1 {
		poolSize = 1
	}

	e := &Engine{
		pool:    make(chan *gosseract.Client, poolSize),
		clients: make([]*gosseract.Client, 0, poolSize),
		lang:    lang,
	}

	for i := 0; i < poolSize; i++ {
		client, err := newPooledClient(lang)
		if err != nil {
			e.Close()
			return nil, fmt.Errorf("tesseract client %d: %w", i, err)
		}
		e.clients = append(e.clients, client)
		e.pool <- client
	}

	return e, nil
}

func newPooledClient(lang string) (*gosseract.Client, error) {
	client := gosseract.NewClient()
	if err := client.SetLanguage(lang); err != nil {
		if err2 := client.SetLanguage("eng"); err2 != nil {
			_ = client.Close()
			return nil, fmt.Errorf("tesseract lang: %w", err)
		}
	}
	return client, nil
}

// Acquire returns a Tesseract client from the pool.
func (e *Engine) Acquire() *gosseract.Client {
	return <-e.pool
}

// Release returns a client to the pool.
func (e *Engine) Release(client *gosseract.Client) {
	e.pool <- client
}

// Close shuts down all pooled clients.
func (e *Engine) Close() error {
	for _, client := range e.clients {
		_ = client.Close()
	}
	e.clients = nil
	return nil
}