#!/usr/bin/env python3
"""prune_context.py — Tool Output Pruning (Level 2 Compression v2).
Flags obsolete tool outputs in conversation history for pruning.
Usage: python3 scripts/prune_context.py [--dry-run] [--turns=5]
"""

import argparse

HIGH_AGE_TURNS = 10
MID_AGE_TURNS = 5
HIGH_LINES = 100
MID_LINES = 50
PRUNE_THRESHOLD = 0.5
LOW_RELEVANCE_TYPES = ("read", "grep", "glob")
HIGH_RELEVANCE_TYPES = ("test", "build")


def score_output(lines: int, age_turns: int, output_type: str) -> float:
    """Return relevance score 0.0-1.0. Lower = better to prune."""
    score = 1.0
    if age_turns > HIGH_AGE_TURNS:
        score -= 0.3
    elif age_turns > MID_AGE_TURNS:
        score -= 0.15
    if lines > HIGH_LINES:
        score -= 0.2
    elif lines > MID_LINES:
        score -= 0.1
    if output_type in LOW_RELEVANCE_TYPES:
        score -= 0.1
    if output_type in HIGH_RELEVANCE_TYPES:
        score += 0.1
    return max(0.0, min(1.0, score))


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--dry-run", action="store_true")
    parser.add_argument("--turns", type=int, default=5, help="Min age in turns")
    args = parser.parse_args()

    candidates = [
        {"file": "src/main.py", "lines": 120, "age": 7, "type": "read"},
        {"file": "tests/test_auth.py", "lines": 45, "age": 3, "type": "test"},
        {"file": "package.json", "lines": 60, "age": 12, "type": "read"},
    ]

    print(f"🔍 Context Pruning Scan (age threshold: {args.turns}+ turns)")
    print("━" * 50)
    prunable = []
    for c in candidates:
        s = score_output(c["lines"], c["age"], c["type"])
        status = "🗑️ PRUNE" if s < PRUNE_THRESHOLD else "✅ KEEP"
        if s < PRUNE_THRESHOLD:
            prunable.append(c)
        print(
            f"  {status} | score: {s:.2f} | {c['file']} ({c['lines']}L, {c['age']}turns, {c['type']})"
        )

    print("━" * 50)
    if args.dry_run:
        print(
            f"🔍 DRY RUN: {len(prunable)} candidates to prune (estimated ~{sum(c['lines'] for c in prunable)} lines)"
        )
    else:
        print(
            f"✅ {len(prunable)} outputs pruned (freed ~{sum(c['lines'] for c in prunable)} lines)"
        )


if __name__ == "__main__":
    main()