#!/usr/bin/env python3
"""
Fetch Flickr _o originals for YFCC photos by tier.
Downloads only if >500px max edge. Resumable -- skips existing files and known-dead hashes.
Prioritizes known-alive users (fast), probes unsampled users, defers dead users.
"""
import csv
import json
import os
import struct
import subprocess
import sys
import time
from collections import defaultdict
from pathlib import Path

MIN_EDGE = 501


def jpeg_dimensions(path: Path) -> tuple[int, int] | None:
    try:
        with open(path, "rb") as f:
            data = f.read(64 * 1024)
        i = 2
        while i < len(data) - 9:
            if data[i] != 0xFF:
                break
            marker = data[i + 1]
            if marker in (0xC0, 0xC1, 0xC2):
                h = struct.unpack(">H", data[i + 5 : i + 7])[0]
                w = struct.unpack(">H", data[i + 7 : i + 9])[0]
                return w, h
            length = struct.unpack(">H", data[i + 2 : i + 4])[0]
            i += 2 + length
    except Exception:
        pass
    return None


def restore_mtime(dest: Path, date_iso: str) -> None:
    """Set file mtime from manifest date so Lightcella uses it as fallback."""
    if not date_iso:
        return
    try:
        from datetime import datetime
        dt = datetime.fromisoformat(date_iso.replace("Z", "+00:00"))
        ts = dt.timestamp()
        if ts > 0:
            os.utime(dest, (ts, ts))
    except (ValueError, OSError):
        pass


def fetch_one(row: dict, out_dir: Path) -> tuple[str, dict | None]:
    """Returns (status, result). status: 'ok', 'small', 'dead', 'rate_limited'."""
    h = row["hash"]
    dest = out_dir / f"{h}.jpg"

    if dest.is_file() and dest.stat().st_size > 0:
        dims = jpeg_dimensions(dest)
        if dims and max(dims) >= MIN_EDGE:
            return "ok", {"hash": h, "width": dims[0], "height": dims[1]}
        return "small", None

    sid, pid, sec = row["serverid"], row["photoid"], row["secret"]
    url = f"https://live.staticflickr.com/{sid}/{pid}_{sec}_o.jpg"

    r = subprocess.run(
        ["curl", "-sL", "-o", str(dest), "-w", "%{http_code}", url,
         "--connect-timeout", "3", "--max-time", "10"],
        capture_output=True, text=True, timeout=15,
    )
    http_code = r.stdout.strip()

    if http_code == "429":
        dest.unlink(missing_ok=True)
        return "rate_limited", None

    if r.returncode != 0 or not dest.is_file() or dest.stat().st_size < 1000:
        dest.unlink(missing_ok=True)
        return "dead", None

    dims = jpeg_dimensions(dest)
    if not dims or max(dims) < MIN_EDGE:
        dest.unlink(missing_ok=True)
        return "small", None

    restore_mtime(dest, row.get("date_iso", ""))
    return "ok", {"hash": h, "width": dims[0], "height": dims[1]}


def process_batch(rows: list[dict], out_dir: Path, out_f, dead_f, counters: dict,
                   base_delay: float = 1.0) -> list[dict]:
    """Process rows sequentially with per-request delay. Retries 429s inline."""
    skipped = []
    consecutive_429 = 0

    for row in rows:
        time.sleep(base_delay)

        status, result = None, None
        for attempt in range(3):
            status, result = fetch_one(row, out_dir)
            if status != "rate_limited":
                break
            wait = 5 + attempt * 5
            print(f"    429 on attempt {attempt+1}, waiting {wait}s...", flush=True)
            time.sleep(wait)

        if status == "rate_limited":
            consecutive_429 += 1
            if consecutive_429 >= 5:
                print(f"    {consecutive_429} consecutive 429s, cooling down 60s...", flush=True)
                time.sleep(60)
                consecutive_429 = 0
        else:
            consecutive_429 = 0

        if status == "ok":
            counters["ok"] += 1
            out_f.write(json.dumps(result) + "\n")
            out_f.flush()
        elif status == "rate_limited":
            counters["rate_limited"] += 1
            skipped.append(row)
        elif status == "small":
            counters["small"] += 1
            dead_f.write(row["hash"] + "\n")
            dead_f.flush()
        else:
            counters["dead"] += 1
            dead_f.write(row["hash"] + "\n")
            dead_f.flush()

    return skipped


def main():
    import argparse
    parser = argparse.ArgumentParser(description="Fetch Flickr originals for YFCC manifest")
    parser.add_argument("--manifest", type=Path, default=Path("manifest.tsv"),
                        help="Path to manifest TSV (default: manifest.tsv)")
    parser.add_argument("--out-dir", type=Path, default=Path("photos"),
                        help="Directory for downloaded JPEGs (default: photos/)")
    parser.add_argument("--results-file", type=Path, default=Path("flickr_originals.jsonl"),
                        help="JSONL tracking successful downloads (default: flickr_originals.jsonl)")
    parser.add_argument("--dead-file", type=Path, default=Path("flickr_dead.txt"),
                        help="File tracking dead/small hashes (default: flickr_dead.txt)")
    parser.add_argument("--tiers", default="medium,large",
                        help="Comma-separated resolution tiers to fetch (default: medium,large)")
    parser.add_argument("--fast-delay", type=float, default=0.3,
                        help="Delay for known-alive users (default: 0.3)")
    parser.add_argument("--probe-delay", type=float, default=1.0,
                        help="Delay for probing unsampled users (default: 1.0)")
    args = parser.parse_args()

    tiers = set(args.tiers.split(","))
    out_dir = args.out_dir
    results_file = args.results_file
    dead_file = args.dead_file

    out_dir.mkdir(parents=True, exist_ok=True)

    # Load manifest rows for requested tiers
    all_rows = []
    with open(args.manifest) as f:
        for row in csv.DictReader(f, delimiter="\t"):
            if row["resolution_tier"] in tiers:
                all_rows.append(row)

    # Resume: skip already-fetched and known-dead
    done_hashes = set()
    if results_file.is_file():
        for line in results_file.read_text().splitlines():
            done_hashes.add(json.loads(line)["hash"])
    dead_hashes = set()
    if dead_file.is_file():
        dead_hashes = set(dead_file.read_text().splitlines())

    skip = done_hashes | dead_hashes

    # Group remaining photos by user
    user_rows = defaultdict(list)
    for r in all_rows:
        if r["hash"] not in skip:
            user_rows[r["uid"]].append(r)

    # Classify users from prior data
    all_by_uid = defaultdict(list)
    for r in all_rows:
        all_by_uid[r["uid"]].append(r["hash"])

    alive_uids = set()
    dead_uids = set()
    unsampled_uids = set()
    for uid in user_rows:
        if any(h in done_hashes for h in all_by_uid[uid]):
            alive_uids.add(uid)
        elif any(h in dead_hashes for h in all_by_uid[uid]):
            dead_uids.add(uid)
        else:
            unsampled_uids.add(uid)

    n_remaining = sum(len(v) for v in user_rows.values())
    print(f"Tiers: {args.tiers} | {len(all_rows)} total, {len(done_hashes)} kept, "
          f"{len(dead_hashes)} known dead, {n_remaining} to probe")
    print(f"  Users: {len(alive_uids)} alive, {len(unsampled_uids)} unsampled, {len(dead_uids)} dead")
    print(f"  Delays: {args.fast_delay}s fast, {args.probe_delay}s probe")

    counters = {"ok": len(done_hashes), "dead": 0, "small": 0, "rate_limited": 0}

    with open(results_file, "a") as out_f, open(dead_file, "a") as dead_f:

        def fetch_user(uid, rows, delay):
            return process_batch(rows, out_dir, out_f, dead_f, counters, base_delay=delay)

        all_rate_limited = []
        probed = 0

        # Phase 1: known-alive users (fast)
        for uid in sorted(alive_uids):
            rows = user_rows.pop(uid, [])
            if not rows:
                continue
            rl = fetch_user(uid, rows, args.fast_delay)
            all_rate_limited.extend(rl)
            probed += len(rows)

        if probed:
            print(f"  alive-users done ({probed} photos): {counters['ok']:,} kept, "
                  f"{counters['dead']:,} dead, {counters['small']:,} small", flush=True)

        # Phase 2: unsampled users -- probe 1, if alive fast-fetch rest
        unsampled_list = sorted(unsampled_uids)
        for i, uid in enumerate(unsampled_list):
            rows = user_rows.pop(uid, [])
            if not rows:
                continue

            rest = rows[1:]
            ok_before = counters["ok"]
            rl = fetch_user(uid, [rows[0]], args.probe_delay)
            all_rate_limited.extend(rl)
            probed += 1

            if counters["ok"] > ok_before:
                if rest:
                    rl = fetch_user(uid, rest, args.fast_delay)
                    all_rate_limited.extend(rl)
                    probed += len(rest)
            elif rest:
                all_rate_limited.extend(rest)

            if (i + 1) % 200 == 0:
                print(f"  unsampled {i+1:,}/{len(unsampled_list):,} users: {counters['ok']:,} kept, "
                      f"{counters['dead']:,} dead, {counters['small']:,} small, "
                      f"{counters['rate_limited']:,} rate-limited", flush=True)

        print(f"  unsampled done: {counters['ok']:,} kept, {counters['dead']:,} dead, "
              f"{counters['small']:,} small", flush=True)

        # Phase 3: known-dead users
        for uid in sorted(dead_uids):
            rows = user_rows.pop(uid, [])
            if not rows:
                continue
            rl = fetch_user(uid, rows, args.probe_delay)
            all_rate_limited.extend(rl)
            probed += len(rows)

        print(f"  dead-users done: {counters['ok']:,} kept, {counters['dead']:,} dead", flush=True)

        # Phase 4: deferred/rate-limited
        if all_rate_limited:
            print(f"  Deferred/rate-limited: {len(all_rate_limited)} remaining at {args.probe_delay}s", flush=True)
            still_rl = process_batch(all_rate_limited, out_dir, out_f, dead_f, counters)
            if still_rl:
                print(f"  {len(still_rl)} still rate-limited after final pass", flush=True)

    n_files = sum(1 for f in out_dir.iterdir() if f.suffix == ".jpg" and f.stat().st_size > 0)
    print(f"\nDone. {counters['ok']:,} hi-res, {counters['dead']:,} dead, "
          f"{counters['small']:,} small, {counters['rate_limited']:,} still rate-limited")
    print(f"{n_files:,} total files on disk")


if __name__ == "__main__":
    main()