"""
OCR module with support for EasyOCR and Doctr.
Provides the `extract_text` function that accepts a cropped bounding box and image,
and runs OCR based on the selected engine ("easyocr" or "doctr").
"""

import numpy as np
from PIL import Image
import cv2
from textblob import TextBlob
from device_config import get_device

# OCR engine flags
USE_EASYOCR = True
USE_DOCTR = False

# Import EasyOCR if available
try:
    import easyocr
    reader = easyocr.Reader(['en'], gpu=(get_device() == "cuda"))
    print(f"✅ EasyOCR reader initialized on: {get_device()}")
    USE_EASYOCR = True
except ImportError:
    print("⚠️ EasyOCR not installed. Falling back if Doctr is available.")

# Import Doctr if available
try:
    from doctr.io import DocumentFile
    from doctr.models import ocr_predictor
    doctr_model = ocr_predictor(pretrained=True)
    print("✅ Doctr model loaded.")
    USE_DOCTR = True
except ImportError:
    print("⚠️ Doctr not installed.")

def expand_bbox(bbox, image_size, pad=10):
    """Expand a bounding box by padding within image bounds."""
    x1, y1, x2, y2 = bbox
    x1 = max(0, x1 - pad)
    y1 = max(0, y1 - pad)
    x2 = min(image_size[0], x2 + pad)
    y2 = min(image_size[1], y2 + pad)
    return [x1, y1, x2, y2]

def clean_text(text):
    """Use TextBlob to autocorrect basic OCR errors."""
    blob = TextBlob(text)
    return str(blob.correct())

def extract_text(image, bbox, debug=False, engine="easyocr"):
    """
    Run OCR on a cropped region using EasyOCR or Doctr.

    Parameters:
        image (PIL.Image): Full input image.
        bbox (list): [x1, y1, x2, y2] bounding box.
        debug (bool): Enable debug output.
        engine (str): 'easyocr' or 'doctr'.

    Returns:
        str: Cleaned OCR output.
    """
    # Expand and crop image region
    bbox = expand_bbox(bbox, image.size, pad=10)
    x1, y1, x2, y2 = bbox
    cropped = image.crop((x1, y1, x2, y2))

    # Convert to OpenCV grayscale
    cv_img = np.array(cropped)
    gray = cv2.cvtColor(cv_img, cv2.COLOR_RGB2GRAY)

    # Enhance contrast using CLAHE (Contrast Limited Adaptive Histogram Equalization)
    clahe = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
    enhanced = clahe.apply(gray)

    # Apply adaptive threshold for better text separation
    thresh = cv2.adaptiveThreshold(enhanced, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 11, 4)

    # Resize for better OCR resolution
    resized = cv2.resize(thresh, (0, 0), fx=2.5, fy=2.5, interpolation=cv2.INTER_LINEAR)

    # Convert to RGB (some OCR engines expect 3-channel images)
    preprocessed = cv2.cvtColor(resized, cv2.COLOR_GRAY2RGB)

    if debug:
        Image.fromarray(preprocessed).save(f"debug_ocr_crop_{x1}_{y1}.png")

    if engine == "doctr" and USE_DOCTR:
        try:
            doc = DocumentFile.from_images([Image.fromarray(preprocessed)])
            result = doctr_model(doc)
            out_text = " ".join([b.value for b in result.pages[0].blocks])
            if debug:
                print(f"📘 Doctr OCR: {out_text}")
            return clean_text(out_text)
        except Exception as e:
            if debug:
                print(f"❌ Doctr failed: {e}")
            return ""

    elif engine == "easyocr" and USE_EASYOCR:
        try:
            results = reader.readtext(preprocessed, paragraph=False, min_size=10)
            filtered = []
            for r in results:
                text = r[1].strip()
                conf = r[2]
                if conf > 0.5 and len(text) > 2 and any(c.isalnum() for c in text):
                    filtered.append(r)

            # Remove duplicates by bounding box IoU overlap
            final = []
            seen = set()
            for r in filtered:
                t = r[1].strip()
                if t.lower() not in seen:
                    seen.add(t.lower())
                    final.append(r)

            final.sort(key=lambda r: (r[0][0][1], r[0][0][0]))
            text = " ".join([r[1] for r in final]).strip()

            if debug:
                for r in final:
                    print(f"📱 EasyOCR: {r[1]} (conf: {r[2]:.2f})")

            return clean_text(text) if text else ""
        except Exception as e:
            if debug:
                print(f"❌ EasyOCR failed: {e}")
            return ""

    else:
        if debug:
            print(f"⚠️ Unsupported OCR engine: {engine} or not available.")
        return ""

def count_elements(boxes, arrows, debug=False):
    """Return count of boxes and arrows detected."""
    box_count = len(boxes)
    arrow_count = len(arrows)
    if debug:
        print(f"📦 Boxes: {box_count} | ➡️ Arrows: {arrow_count}")
    return {"box_count": box_count, "arrow_count": arrow_count}

def validate_structure(flowchart_json, expected_boxes=None, expected_arrows=None, debug=False):
    """Validate flowchart structure consistency based on expected counts."""
    actual_boxes = len(flowchart_json.get("steps", []))
    actual_arrows = len(flowchart_json.get("edges", [])) if "edges" in flowchart_json else None

    if debug:
        print(f"🔍 JSON boxes: {actual_boxes}, edges: {actual_arrows}")

    return {
        "boxes_valid": (expected_boxes is None or expected_boxes == actual_boxes),
        "arrows_valid": (expected_arrows is None or expected_arrows == actual_arrows)
    }