"""
Lab 1 - Eksperimen Chunking (15 menit)
Hanya butuh library pypdf:   pip install pypdf

Cara jalankan (pilih salah satu):
    python lab_1.py                                  -> otomatis pakai PDF pertama di folder dokumen/
    python lab_1.py dokumen/panduan_akademik.pdf     -> pakai PDF tertentu
    python lab_1.py dokumen/panduan_akademik.pdf --overlap 0.2
"""

import argparse
import random
import re
from pathlib import Path

from pypdf import PdfReader

UKURAN_LIST = [500, 1000, 1500]


def baca_pdf(path):
    """Baca seluruh teks dari satu file PDF."""
    reader = PdfReader(str(path))
    halaman = [(p.extract_text() or "") for p in reader.pages]
    teks = "\n".join(halaman)
    return re.sub(r"[ \t]+", " ", teks).strip()


def potong(teks, ukuran=1000, overlap=0.15):
    """Potong teks jadi chunk berukuran `ukuran` karakter dengan overlap (0-1)."""
    langkah = max(1, int(ukuran * (1 - overlap)))
    chunks = []
    for mulai in range(0, len(teks), langkah):
        potongan = teks[mulai:mulai + ukuran].strip()
        if potongan:
            chunks.append(potongan)
        if mulai + ukuran >= len(teks):
            break
    return chunks


def cari_pdf_default():
    daftar = sorted(Path("dokumen").glob("*.pdf"))
    if not daftar:
        raise SystemExit("Tidak ada PDF di folder dokumen/. Taruh PDF di sana atau tulis path-nya.")
    return daftar[0]


def main():
    p = argparse.ArgumentParser(description="Lab 1: eksperimen chunking")
    p.add_argument("pdf", nargs="?", help="Path PDF (kosongkan untuk pakai PDF pertama di dokumen/)")
    p.add_argument("--overlap", type=float, default=0.15, help="Overlap 0.10 - 0.20 (default 0.15)")
    args = p.parse_args()

    path = Path(args.pdf) if args.pdf else cari_pdf_default()
    print(f"File: {path}\n")

    # 1. Baca PDF, cetak 500 karakter pertama
    teks = baca_pdf(path)
    print(f"=== 1. Hasil baca PDF ({len(teks)} karakter total) ===")
    print(teks[:500])

    # 2. Potong dengan tiga ukuran, catat jumlah chunk
    print("\n=== 2. Jumlah chunk per pengaturan ===")
    hasil = {}
    for ukuran in UKURAN_LIST:
        chunks = potong(teks, ukuran, args.overlap)
        hasil[ukuran] = chunks
        print(f"  ukuran={ukuran:<5} overlap={args.overlap:.0%}  ->  {len(chunks)} chunk")

    # 3. Lihat 3 chunk acak tiap ukuran
    print("\n=== 3. Tiga chunk acak per ukuran (terpotong di tengah kalimat/tabel?) ===")
    for ukuran, chunks in hasil.items():
        print(f"\n--- ukuran {ukuran} ---")
        for c in random.sample(chunks, min(3, len(chunks))):
            awal_rapi = c[0].isupper() or c[0].isdigit()
            akhir_rapi = c[-1] in ".!?:"
            print(f"[awal rapi: {awal_rapi} | akhir rapi: {akhir_rapi}]")
            print(c)
            print("." * 40)


if __name__ == "__main__":
    main()