"""Compare forensic snapshots and print diff tables."""
import json
import sys
from pathlib import Path

def load(p):
    return json.loads(Path(p).read_text(encoding="utf-8-sig"))

def diff_table(a, b, keys):
    rows = []
    for k in keys:
        va, vb = a.get(k), b.get(k)
        changed = va != vb
        rows.append((k, va, vb, "CHANGED" if changed else "same"))
    return rows

def print_table(title, rows):
    print(f"\n=== {title} ===")
    print(f"{'Property':<22} {'Before':<40} {'After':<40} {'Status'}")
    for k, va, vb, st in rows:
        sa = json.dumps(va) if not isinstance(va, str) else va
        sb = json.dumps(vb) if not isinstance(vb, str) else vb
        if len(sa) > 38: sa = sa[:35] + "..."
        if len(sb) > 38: sb = sb[:35] + "..."
        print(f"{k:<22} {sa:<40} {sb:<40} {st}")

def compare_advances(orig, new):
    oa, na = orig or [], new or []
    diffs = []
    for i in range(max(len(oa), len(na))):
        ov = oa[i] if i < len(oa) else None
        nv = na[i] if i < len(na) else None
        if ov != nv:
            diffs.append((i, ov, nv))
    return diffs

def main():
    extract_path = Path(sys.argv[1] if len(sys.argv) > 1 else "forensic_extract_out.json")
    wasm_path = Path(sys.argv[2] if len(sys.argv) > 2 else "forensic_wasm_out.json")
    ex = load(extract_path)
    wasm = load(wasm_path)

    keys = [
        "text", "fontId", "fontName", "fontSize", "color",
        "glyphCount", "advanceCount", "paragraphWidth", "baseline", "lineHeight",
        "origLinesProvided",
    ]

    orig = ex["original"]
    entry_payload = ex["editEntry"]
    one_payload = ex["editOne"]

  # WASM layout snapshots
    from forensic_extract import snapshot_from_wasm_layout, para_signature  # type: ignore
    seed_fn = orig.get("fontName", "")
    entry_wasm = snapshot_from_wasm_layout("ENTRY_WASM", wasm["editEntryWasm"]["layout"], seed_fn)
    one_wasm = snapshot_from_wasm_layout("ONE_WASM", wasm["editOneWasm"]["layout"], seed_fn)

    print_table("ORIGINAL vs EDIT_MODE_ENTRY (payload)", diff_table(orig, entry_payload, keys))
    print_table("ORIGINAL vs EDIT_MODE_ENTRY (WASM layout)", diff_table(orig, entry_wasm, keys))

    adv_diff_entry = compare_advances(orig.get("advances"), entry_wasm.get("advances"))
    if adv_diff_entry:
        print(f"\nAdvance diffs ORIGINAL vs ENTRY_WASM: {len(adv_diff_entry)} positions")
        for i, ov, nv in adv_diff_entry[:20]:
            print(f"  [{i}] {ov} -> {nv}")
    else:
        print("\nAdvance arrays IDENTICAL: ORIGINAL vs ENTRY_WASM")

    print_table("EDIT_ENTRY vs AFTER_ONE_CHAR (payload)", diff_table(entry_payload, one_payload, keys))
    print_table("ENTRY_WASM vs ONE_WASM", diff_table(entry_wasm, one_wasm, keys))

    adv_diff_one = compare_advances(entry_wasm.get("advances"), one_wasm.get("advances"))
    if adv_diff_one:
        print(f"\nAdvance diffs ENTRY_WASM vs ONE_WASM: {len(adv_diff_one)} positions")
        for i, ov, nv in adv_diff_one[:20]:
            print(f"  [{i}] {ov} -> {nv}")

    # Line widths
    print("\n=== LINE WIDTHS ===")
    print(f"Original lineWidths: {orig.get('lineWidths')}")
    print(f"Entry WASM lineWidths: {entry_wasm.get('lineWidths')}")
    print(f"One WASM lineWidths: {one_wasm.get('lineWidths')}")

    # Signatures chain
    sigs = {
        "original": para_signature(orig),
        "entry_payload": para_signature(entry_payload),
        "entry_wasm": para_signature(entry_wasm),
        "one_payload": para_signature(one_payload),
        "one_wasm": para_signature(one_wasm),
    }
    print("\n=== SIGNATURE CHAIN ===")
    prev = None
    for name, sig in sigs.items():
        changed = prev and sig != prev
        print(f"  {name}: {sig}" + ("  <-- FIRST CHANGE from " + prev_name if changed else ""))
        if changed and prev:
            pass
        prev_name = name
        prev = sig

    # First mutation
    chain = list(sigs.items())
    base = chain[0][1]
    for i in range(1, len(chain)):
        if chain[i][1] != base:
            print(f"\nFIRST SIGNATURE CHANGE: {chain[i][0]} (vs original)")
            break

if __name__ == "__main__":
    main()