"""Basic text validation examples.

Demonstrates core Veritext functionality:
- Single metric scoring (BLEU, ROUGE)
- Validator usage with thresholds
- Composite validators (all_of, any_of)
- Constraint validators (length, readability)
"""

from veritext.core.types import ValidationContext
from veritext.metrics import Bleu, Rouge
from veritext.validators import (
    all_of,
    any_of,
    bleu,
    contains,
    excludes,
    length,
    readability,
    rouge,
)


def metric_scoring_example() -> None:
    """Score text using individual metrics."""
    candidate = "The quick brown fox jumps over the lazy dog."
    reference = "A fast brown fox leaps over a sleepy dog."

    # BLEU scoring (translation quality)
    bleu_metric = Bleu()
    bleu_result = bleu_metric.score(candidate, reference)
    print("BLEU Scores:")
    print(f"  BLEU-1: {bleu_result.bleu1:.3f}")
    print(f"  BLEU-4: {bleu_result.bleu4:.3f}")
    print(f"  Brevity penalty: {bleu_result.brevity_penalty:.3f}")

    # ROUGE scoring (summary quality)
    rouge_metric = Rouge()
    rouge_result = rouge_metric.score(candidate, reference)
    print("\nROUGE Scores:")
    print(f"  ROUGE-1 F1: {rouge_result.rouge1.fmeasure:.3f}")
    print(f"  ROUGE-L F1: {rouge_result.rouge_l.fmeasure:.3f}")


def validator_example() -> None:
    """Use validators to make pass/fail decisions."""
    reference = "Machine learning models require training data."
    candidate = "ML models need training data to learn patterns."

    context = ValidationContext(reference=reference)

    # BLEU validator with minimum threshold
    bleu_validator = bleu(min_score=0.3)
    result = bleu_validator.check(candidate, context)
    print(f"\nBLEU validation (min 0.3): {'PASS' if result.passed else 'FAIL'}")

    # ROUGE validator
    rouge_validator = rouge(min_score=0.5)
    result = rouge_validator.check(candidate, context)
    print(f"ROUGE validation (min 0.5): {'PASS' if result.passed else 'FAIL'}")


def composite_validator_example() -> None:
    """Combine validators with all_of and any_of."""
    reference = "The product launch exceeded all expectations."
    candidate = "The product release performed beyond expectations."

    context = ValidationContext(reference=reference)

    # All checks must pass
    strict_validator = all_of(
        [
            bleu(min_score=0.2),
            rouge(min_score=0.4),
            length(max_chars=100),
        ]
    )
    result = strict_validator.check(candidate, context)
    print(f"\nStrict (all_of): {'PASS' if result.passed else 'FAIL'}")
    if not result.passed:
        print(f"  Failures: {result.failure_summary}")

    # At least one check must pass
    flexible_validator = any_of(
        [
            bleu(min_score=0.8),  # Unlikely to pass
            rouge(min_score=0.4),  # More likely
        ]
    )
    result = flexible_validator.check(candidate, context)
    print(f"Flexible (any_of): {'PASS' if result.passed else 'FAIL'}")


def constraint_validator_example() -> None:
    """Use constraint validators for text properties."""
    text = "This short guide explains the basics clearly."
    context = ValidationContext()  # No reference needed for constraints

    # Length constraints
    length_validator = length(min_chars=20, max_chars=100, min_words=5, max_words=20)
    result = length_validator.check(text, context)
    print(f"\nLength check: {'PASS' if result.passed else 'FAIL'}")

    # Readability (Flesch-Kincaid)
    readability_validator = readability(max_grade=10.0)
    result = readability_validator.check(text, context)
    print(f"Readability (grade <= 10): {'PASS' if result.passed else 'FAIL'}")

    # Content patterns
    contains_validator = contains(patterns=["guide", "basics"])
    result = contains_validator.check(text, context)
    print(f"Contains required terms: {'PASS' if result.passed else 'FAIL'}")

    excludes_validator = excludes(patterns=["error", "warning"])
    result = excludes_validator.check(text, context)
    print(f"Excludes forbidden terms: {'PASS' if result.passed else 'FAIL'}")


def main() -> None:
    """Run all examples."""
    print("=" * 60)
    print("Veritext Basic Validation Examples")
    print("=" * 60)

    metric_scoring_example()
    validator_example()
    composite_validator_example()
    constraint_validator_example()

    print("\n" + "=" * 60)
    print("All examples completed.")


if __name__ == "__main__":
    main()