"""Backfill MMP and best-effort records into existing BAS activity JSONs.

Reads 1Hz timeseries (power_w, speed_kmh, elevation_m) from already-extracted
detail JSONs — no need to re-parse source FIT/GPX/TCX files.

Run once after upgrading to the MMP + records extract pipeline, or whenever
the computation logic changes and you want to refresh all activities.

Usage:
    uv run python scripts/backfill.py [--data-dir ~/src/bincio_data]
"""

import json
import sys
from pathlib import Path

import click
from rich.console import Console
from rich.progress import BarColumn, MofNCompleteColumn, Progress, TextColumn, TimeElapsedColumn

console = Console()

# ── MMP ───────────────────────────────────────────────────────────────────────

MMP_DURATIONS_S = [1, 2, 5, 10, 15, 20, 30, 60, 120, 180, 300, 600, 1200, 1800, 3600]


def _compute_mmp(power_w: list) -> list[list[int]] | None:
    samples = [w for w in power_w if w is not None]
    if len(samples) < 2:
        return None
    n = len(samples)
    results = []
    for d in MMP_DURATIONS_S:
        if d > n:
            break
        window_sum = sum(samples[:d])
        best = window_sum
        for i in range(1, n - d + 1):
            window_sum += samples[i + d - 1] - samples[i - 1]
            if window_sum > best:
                best = window_sum
        results.append([d, round(best / d)])
    return results if results else None


# ── Best efforts ──────────────────────────────────────────────────────────────

BEST_EFFORT_DISTANCES: dict[str, list[float]] = {
    "running": [0.4, 1.0, 1.609, 5.0, 10.0, 21.097, 42.195],
    "cycling": [5.0, 10.0, 20.0, 50.0, 100.0],
    "swimming": [0.1, 0.2, 0.5, 1.0, 2.0],
}


def _fastest_time(speed_kmh: list, target_km: float) -> int | None:
    left = 0
    window_dist = 0.0
    best_s = None
    for right, spd in enumerate(speed_kmh):
        window_dist += (spd or 0.0) / 3600.0
        while window_dist >= target_km and left <= right:
            window_s = right - left + 1
            if best_s is None or window_s < best_s:
                best_s = window_s
            window_dist -= (speed_kmh[left] or 0.0) / 3600.0
            left += 1
    return best_s


def _compute_best_efforts(speed_kmh: list, sport: str) -> list[list[float]] | None:
    targets = BEST_EFFORT_DISTANCES.get(sport, [])
    if not targets or not speed_kmh:
        return None
    results = []
    for d_km in targets:
        t_s = _fastest_time(speed_kmh, d_km)
        if t_s is not None:
            results.append([d_km, t_s])
    return results if results else None


def _compute_best_climb(elevation_m: list) -> float | None:
    valid = [e for e in elevation_m if e is not None]
    if len(valid) < 2:
        return None
    max_gain = current = 0.0
    for a, b in zip(valid, valid[1:]):
        current = max(0.0, current + (b - a))
        if current > max_gain:
            max_gain = current
    return round(max_gain, 1) if max_gain > 0 else None


# ── Main ──────────────────────────────────────────────────────────────────────

@click.command()
@click.option("--data-dir", default="~/src/bincio_data", show_default=True)
@click.option("--dry-run", is_flag=True)
@click.option("--force", is_flag=True, help="Recompute even if fields already present.")
def main(data_dir: str, dry_run: bool, force: bool) -> None:
    """Backfill mmp, best_efforts, and best_climb_m into existing activity JSONs."""
    data = Path(data_dir).expanduser()
    acts_dir = data / "activities"

    if not acts_dir.exists():
        console.print(f"[red]Activities dir not found: {acts_dir}[/red]")
        sys.exit(1)

    jsons = sorted(acts_dir.glob("*.json"))
    console.print(f"Found [bold]{len(jsons)}[/bold] activity JSONs in {acts_dir}")

    updated = skipped = 0

    with Progress(
        TextColumn("[progress.description]{task.description}"),
        BarColumn(), MofNCompleteColumn(), TimeElapsedColumn(),
        console=console,
    ) as progress:
        task = progress.add_task("Backfilling…", total=len(jsons))

        for path in jsons:
            progress.advance(task)
            try:
                detail = json.loads(path.read_text())
            except Exception:
                skipped += 1
                continue

            already_done = (
                detail.get("mmp") is not None
                and detail.get("best_efforts") is not None
                or detail.get("best_efforts") == []  # explicitly empty = computed, no results
            )
            if already_done and not force:
                skipped += 1
                continue

            sport = detail.get("sport", "other")
            ts = detail.get("timeseries") or {}
            power_w   = ts.get("power_w") or []
            speed_kmh = ts.get("speed_kmh") or []
            ele_m     = ts.get("elevation_m") or []

            changed = False

            if detail.get("mmp") is None or force:
                mmp = _compute_mmp(power_w)
                if mmp is not None:
                    detail["mmp"] = mmp
                    changed = True

            if detail.get("best_efforts") is None or force:
                be = _compute_best_efforts(speed_kmh, sport)
                detail["best_efforts"] = be  # store None or list (None = sport has no targets)
                changed = True

            if (detail.get("best_climb_m") is None or force) and sport == "cycling":
                bc = _compute_best_climb(ele_m)
                if bc is not None:
                    detail["best_climb_m"] = bc
                    changed = True

            if changed:
                if not dry_run:
                    path.write_text(json.dumps(detail, indent=2, ensure_ascii=False))
                updated += 1

    console.print(
        f"\n[green]Done.[/green] "
        f"Updated [bold]{updated}[/bold], skipped [bold]{skipped}[/bold]."
    )
    if dry_run:
        console.print("[yellow]Dry run — nothing written.[/yellow]")
        return

    # Patch index.json summaries
    console.print("Patching index.json summaries…")
    index_path = data / "index.json"
    index = json.loads(index_path.read_text())

    lookup: dict[str, dict] = {}
    for path in acts_dir.glob("*.json"):
        try:
            d = json.loads(path.read_text())
            lookup[d["id"]] = {
                "mmp": d.get("mmp"),
                "best_efforts": d.get("best_efforts"),
                "best_climb_m": d.get("best_climb_m"),
            }
        except Exception:
            pass

    patched = 0
    for s in index.get("activities", []):
        row = lookup.get(s["id"])
        if not row:
            continue
        if row.get("mmp") and not s.get("mmp"):
            s["mmp"] = row["mmp"]; patched += 1
        if row.get("best_efforts") is not None and s.get("best_efforts") is None:
            s["best_efforts"] = row["best_efforts"]; patched += 1
        if row.get("best_climb_m") and not s.get("best_climb_m"):
            s["best_climb_m"] = row["best_climb_m"]; patched += 1

    index_path.write_text(json.dumps(index, indent=2, ensure_ascii=False))
    console.print(f"  {patched} fields patched in index.json.")

    # Rebuild athlete.json
    console.print("Rebuilding athlete.json…")
    from bincio.extract.writer import write_athlete_json
    owner = index.get("owner", {})
    athlete_cfg = {k: v for k, v in (owner.get("athlete") or {}).items() if v is not None}
    write_athlete_json(index.get("activities", []), data, athlete_cfg)
    console.print("  athlete.json written.")

    # Re-merge
    console.print("Running merge_all…")
    from bincio.render.merge import merge_all
    n = merge_all(data)
    console.print(f"  merge_all done ({n} sidecars).")


if __name__ == "__main__":
    main()