import re
import io
from typing import List, Any
from pydantic import BaseModel
from abc import ABC, abstractmethod

try:
    from PIL import Image
except ImportError:
    Image = None

class ValidationResult(BaseModel):
    valid: bool
    errors: List[str]

class IBatchValidator(ABC):
    @abstractmethod
    def validate_batch_size(self, batch: Any) -> ValidationResult: pass
    @abstractmethod
    def check_sequence_continuity(self, batch: Any, expected_start: int) -> ValidationResult: pass
    @abstractmethod
    def validate_naming_convention(self, filenames: List[str]) -> ValidationResult: pass
    @abstractmethod
    def validate_format(self, image_data: bytes) -> ValidationResult: pass

class BatchValidator(IBatchValidator):
    """H08: Validates image batch integrity, sequence continuity, and format."""
    def validate_batch_size(self, batch: Any) -> ValidationResult:
        if len(batch.images) < 10: return ValidationResult(valid=False, errors=[f"Batch size {len(batch.images)} below minimum 10"])
        if len(batch.images) > 50: return ValidationResult(valid=False, errors=[f"Batch size {len(batch.images)} exceeds maximum 50"])
        return ValidationResult(valid=True, errors=[])

    def check_sequence_continuity(self, batch: Any, expected_start: int) -> ValidationResult:
        try:
            seqs = [int(re.match(r"AD(\d{6})\.", f, re.I).group(1)) for f in batch.filenames]
            if seqs[0] != expected_start: return ValidationResult(valid=False, errors=[f"Expected start {expected_start}"])
            for i in range(len(seqs) - 1):
                if seqs[i+1] != seqs[i] + 1: return ValidationResult(valid=False, errors=["Gap detected"])
            return ValidationResult(valid=True, errors=[])
        except Exception as e:
            return ValidationResult(valid=False, errors=[str(e)])

    def validate_naming_convention(self, filenames: List[str]) -> ValidationResult:
        ptn = re.compile(r"^AD\d{6}\.(jpg|JPG|png|PNG)$")
        errs = [f"Invalid naming for {f}" for f in filenames if not ptn.match(f)]
        return ValidationResult(valid=len(errs) == 0, errors=errs)

    def validate_format(self, image_data: bytes) -> ValidationResult:
        if len(image_data) > 10 * 1024 * 1024: return ValidationResult(valid=False, errors=["Size > 10MB"])
        if not Image: return ValidationResult(valid=True, errors=[])
        try: img = Image.open(io.BytesIO(image_data)); img.verify()
        except Exception as e: return ValidationResult(valid=False, errors=[f"Corrupted: {e}"])
        return ValidationResult(valid=True, errors=[])