"""Parse flow-emitted Plotly HTML files into a compact per-frame JSON dict.

The embedding-sandbox flow writes one standalone HTML per run at
``figs/<stem>.html``. Each HTML contains a ``Plotly.newPlot(...)`` call (which
holds the initial frame) and a ``Plotly.addFrames(...)`` call (which holds the
full animation — including a redundant copy of frame 0). Point data is encoded
with plotly's base64+dtype ("bdata") scheme, so we decode it with ``struct``.

The module is stdlib-only.
"""

from __future__ import annotations

import base64
import json
import re
import struct
from pathlib import Path


_STEM_RE = re.compile(
    r"^(?P<gen>make_.+?)_(?P<emb>[A-Za-z]+)_N(?P<n>\d+)_T(?P<t>\d+)"
    r"_J(?P<j>[\d.]+)_s(?P<s>\d+)$"
)

# plotly's typed-array dtype -> (struct format char, item size bytes)
_DTYPE_MAP = {
    "i1": ("b", 1),
    "u1": ("B", 1),
    "i2": ("h", 2),
    "u2": ("H", 2),
    "i4": ("i", 4),
    "u4": ("I", 4),
    "i8": ("q", 8),
    "u8": ("Q", 8),
    "f4": ("f", 4),
    "f8": ("d", 8),
}


def _decode_bdata(obj):
    # Accepts either a plotly typed-array dict {"dtype","bdata",...} or a plain list.
    if isinstance(obj, list):
        return list(obj)
    if not isinstance(obj, dict) or "bdata" not in obj:
        raise ValueError(f"expected bdata object or list, got {type(obj).__name__}")
    dt = obj.get("dtype")
    if dt not in _DTYPE_MAP:
        raise ValueError(f"unsupported dtype {dt!r}")
    fmt, size = _DTYPE_MAP[dt]
    raw = base64.b64decode(obj["bdata"])
    count = len(raw) // size
    return list(struct.unpack("<" + fmt * count, raw[: count * size]))


def _extract_call_args(txt: str, call_name: str):
    # Locate the LAST occurrence of `call_name(` in the file (plotly's JS
    # bundle mentions Plotly.newPlot in docstrings/code earlier, but the real
    # user-data call is always emitted at the very bottom).
    start = txt.rfind(call_name + "(")
    if start < 0:
        raise ValueError(f"{call_name}( not found")
    open_paren = txt.index("(", start)
    i = open_paren + 1
    depth = 1
    in_str = False
    escape = False
    args: list[str] = []
    cur = i
    n = len(txt)
    while i < n:
        c = txt[i]
        if in_str:
            if escape:
                escape = False
            elif c == "\\":
                escape = True
            elif c == '"':
                in_str = False
        else:
            if c == '"':
                in_str = True
            elif c in "([{":
                depth += 1
            elif c in ")]}":
                depth -= 1
                if depth == 0:
                    args.append(txt[cur:i].strip())
                    return args
            elif c == "," and depth == 1:
                args.append(txt[cur:i].strip())
                cur = i + 1
        i += 1
    raise ValueError(f"unterminated {call_name} arglist")


def _parse_stem(stem: str) -> dict:
    m = _STEM_RE.match(stem)
    if not m:
        raise ValueError(f"stem does not match expected pattern: {stem!r}")
    return {
        "stem": stem,
        "generator": m.group("gen"),
        "embedder": m.group("emb"),
        "num_points": int(m.group("n")),
        "num_timesteps": int(m.group("t")),
        "jitter_scale": float(m.group("j")),
        "seed": int(m.group("s")),
    }


def _trace_xy_by_id(trace: dict) -> tuple[list[int], list[float], list[float]]:
    # Prefer explicit `ids`; fall back to customdata (which in this flow also
    # carries the point id in column 0); finally, fall back to positional index.
    if "ids" in trace:
        ids = _decode_bdata(trace["ids"])
        # ids may arrive as strings too (plotly coerces). If they're strings
        # of digits, we leave them as-is but prefer ints when possible.
        if ids and isinstance(ids[0], str) and ids[0].isdigit():
            ids = [int(v) for v in ids]
    elif "customdata" in trace:
        cd = trace["customdata"]
        if isinstance(cd, dict):
            ids = _decode_bdata(cd)
        else:
            # shape (N, k): pick first column
            ids = [row[0] if isinstance(row, (list, tuple)) else row for row in cd]
    else:
        ids = list(range(len(_decode_bdata(trace["x"]))))
    xs = _decode_bdata(trace["x"])
    ys = _decode_bdata(trace["y"])
    if not (len(ids) == len(xs) == len(ys)):
        raise ValueError(
            f"trace length mismatch: ids={len(ids)} x={len(xs)} y={len(ys)}"
        )
    return ids, xs, ys


def _frame_xy_ordered(traces: list[dict], point_ids: list[int]):
    # Merge possibly multiple traces (one per label-group) back into a single
    # (x, y) pair ordered by point_ids. Ids missing from this frame — points
    # added or removed between frames by the jitter_add_remove path — become
    # `None` so downstream code can skip them.
    by_id: dict[int, tuple[float, float]] = {}
    for t in traces:
        ids, xs, ys = _trace_xy_by_id(t)
        for pid, x, y in zip(ids, xs, ys):
            by_id[pid] = (x, y)
    xs_out = [by_id[pid][0] if pid in by_id else None for pid in point_ids]
    ys_out = [by_id[pid][1] if pid in by_id else None for pid in point_ids]
    return xs_out, ys_out


def _labels_for_ids(traces: list[dict], point_ids: list[int]) -> list[str]:
    # If traces carry distinct names/legendgroups, use that as the per-point
    # class label. When all traces share an empty name (the single-trace case
    # emitted by this flow), labels are uniformly "".
    names = [t.get("name") or t.get("legendgroup") or "" for t in traces]
    if len(traces) <= 1 or all(n == names[0] for n in names):
        return ["" for _ in point_ids]
    by_id: dict[int, str] = {}
    for t, name in zip(traces, names):
        ids, _, _ = _trace_xy_by_id(t)
        for pid in ids:
            by_id[pid] = name
    return [by_id.get(pid, "") for pid in point_ids]


def parse_plotly_run(html_path) -> dict:
    """Parse a flow-emitted plotly HTML into a frames dict suitable for
    the three.js comparison page. Raises ValueError on unrecognised shape."""
    path = Path(html_path)
    stem = path.stem
    meta = _parse_stem(stem)

    txt = path.read_text(encoding="utf-8")

    new_args = _extract_call_args(txt, "Plotly.newPlot")
    if len(new_args) < 3:
        raise ValueError(f"Plotly.newPlot expected >=3 args, got {len(new_args)}")
    initial_traces = json.loads(new_args[1])
    layout = json.loads(new_args[2])

    add_args = _extract_call_args(txt, "Plotly.addFrames")
    if len(add_args) < 2:
        raise ValueError(f"Plotly.addFrames expected 2 args, got {len(add_args)}")
    raw_frames = json.loads(add_args[1])
    if not isinstance(raw_frames, list) or not raw_frames:
        raise ValueError("Plotly.addFrames second arg is not a non-empty list")

    # Establish the stable id set as the UNION of ids across every frame —
    # the flow's jitter_add_remove path intentionally adds/removes points
    # between frames, so no single frame is authoritative. Order is: first
    # appearance across frames, then by numeric id within each frame's new ids.
    seen_ids: list[int] = []
    seen_set: set = set()
    for fr in raw_frames:
        for t in fr.get("data") or []:
            ids, _, _ = _trace_xy_by_id(t)
            for pid in ids:
                if pid not in seen_set:
                    seen_set.add(pid)
                    seen_ids.append(pid)
    if not seen_ids:
        raise ValueError("no point ids recovered from any frame")

    first_frame_traces = raw_frames[0].get("data") or initial_traces
    labels = _labels_for_ids(first_frame_traces, seen_ids)

    frames_out = []
    times = []
    for i, fr in enumerate(raw_frames):
        traces = fr.get("data")
        if not traces:
            raise ValueError(f"frame {i} has no 'data'")
        xs, ys = _frame_xy_ordered(traces, seen_ids)
        frames_out.append({"x": xs, "y": ys})
        times.append(fr.get("name", str(i)))

    # Global bounds across all frames (skipping None placeholders for
    # points that only exist in some frames).
    all_x = [v for fr in frames_out for v in fr["x"] if v is not None]
    all_y = [v for fr in frames_out for v in fr["y"] if v is not None]
    if not all_x or not all_y:
        raise ValueError("no finite x/y values across frames")
    xmin, xmax = min(all_x), max(all_x)
    ymin, ymax = min(all_y), max(all_y)

    title = ""
    try:
        title = layout["title"]["text"] if isinstance(layout.get("title"), dict) else str(layout.get("title") or "")
    except Exception:
        title = ""
    meta["title"] = title

    return {
        "meta": meta,
        "point_ids": seen_ids,
        "labels": labels,
        "times": times,
        "frames": frames_out,
        "bounds": {"x": [xmin, xmax], "y": [ymin, ymax]},
    }


if __name__ == "__main__":
    import sys
    import traceback

    figs_dir = Path("/home/mm/work/dr-sandbox/figs")
    html_files = sorted(figs_dir.glob("*.html"))
    if not html_files:
        print("no .html files in", figs_dir)
        sys.exit(1)

    failures = []
    for p in html_files:
        try:
            out = parse_plotly_run(p)
        except Exception as e:
            failures.append((p.name, str(e)))
            print(f"FAIL  {p.name}: {e}")
            traceback.print_exc()
            continue
        m = out["meta"]
        pids = out["point_ids"]
        frames = out["frames"]
        nT = len(frames)
        f0 = frames[0]
        f0x = [v for v in f0["x"] if v is not None]
        f0y = [v for v in f0["y"] if v is not None]
        xr = (min(f0x), max(f0x)) if f0x else (float("nan"), float("nan"))
        yr = (min(f0y), max(f0y)) if f0y else (float("nan"), float("nan"))
        consistent = all(len(fr["x"]) == len(pids) and len(fr["y"]) == len(pids) for fr in frames)
        present_per_frame = [sum(v is not None for v in fr["x"]) for fr in frames]
        present_rng = (min(present_per_frame), max(present_per_frame))
        print(
            f"OK    {m['stem']}  |ids|={len(pids)} T={nT}  "
            f"present/frame=[{present_rng[0]},{present_rng[1]}]  "
            f"f0 x=[{xr[0]:+.3f},{xr[1]:+.3f}] y=[{yr[0]:+.3f},{yr[1]:+.3f}]  "
            f"consistent={consistent}"
        )

    print()
    if failures:
        print(f"{len(failures)} failure(s):")
        for name, msg in failures:
            print(f"  {name}: {msg}")
    else:
        print(f"all {len(html_files)} files parsed OK")