"""Point-wise benchmark JSON loader.

The expected schema is a flat JSON list of records of the form::

    {
      "video_name": "000434_c.mp4",
      "video_path": "videos/000434_c.mp4",   # relative to the JSON file
      "prompt": "...",
      "source": "vs2",
      "metadata": {
        "visual_score": 4,
        "t2v_score": 4,
        "phy_score": 4
      }
    }

``video_path`` is interpreted relative to the directory that contains the
JSON file (and may also be absolute).
"""
from __future__ import annotations

import json
import os
from typing import Any, Tuple


def _json_records(payload: Any, data_path: str) -> list[dict[str, Any]]:
    if not isinstance(payload, list):
        raise ValueError(
            f"JSON data must be a list of records: {data_path} "
            f"(got {type(payload).__name__})"
        )
    if not all(isinstance(item, dict) for item in payload):
        raise ValueError(f"JSON data must contain objects only: {data_path}")
    return payload


def _resolve_video_path(base_dir: str, video_path: str) -> str:
    """Resolve a record's ``video_path`` against the JSON file's directory."""
    if not isinstance(video_path, str) or not video_path:
        return ""
    if os.path.isabs(video_path):
        return video_path
    return os.path.normpath(os.path.join(base_dir, video_path))


def load_pointwise_data(
    data_path: str,
    num_samples: str = "all",
) -> Tuple[list[dict[str, Any]], list[dict[str, Any]]]:
    """Load a point-wise benchmark JSON.

    Parameters
    ----------
    data_path : str
        Path to the benchmark JSON file.
    num_samples : str
        Either ``"all"`` or a positive integer (as a string) capping the
        number of records.

    Returns
    -------
    (raw_prompts, expanded)
        raw_prompts : list of de-duplicated prompts with their source row
                      indices (handy for any prompt-level step).
        expanded    : list of per-video records ready for scoring.
    """
    data_path = os.path.abspath(data_path)
    base_dir = os.path.dirname(data_path)

    with open(data_path, "r", encoding="utf-8") as f:
        records = _json_records(json.load(f), data_path)
    print(f"[data] Loaded {len(records)} videos from {data_path}")

    if num_samples != "all":
        records = records[: int(num_samples)]
        print(f"[data] Truncated to {len(records)} videos")

    prompt_to_index: dict[str, int] = {}
    raw_prompts: list[dict[str, Any]] = []
    expanded: list[dict[str, Any]] = []

    for row_idx, item in enumerate(records):
        video_name = str(item["video_name"])
        prompt_text = str(item["prompt"])
        source_index = prompt_to_index.get(prompt_text)
        if source_index is None:
            source_index = len(raw_prompts)
            prompt_to_index[prompt_text] = source_index
            raw_prompts.append(
                {"prompt": prompt_text, "prompt_id": source_index, "source_rows": []}
            )
        raw_prompts[source_index]["source_rows"].append(row_idx)

        rel_video_path = item.get("video_path", "")
        local_path = _resolve_video_path(base_dir, rel_video_path)
        source = str(item.get("source", "")).strip()
        metadata = item.get("metadata", {}) or {}
        if not isinstance(metadata, dict):
            metadata = {}

        expanded.append(
            {
                "video_id": f"{row_idx}_{os.path.splitext(video_name)[0]}",
                "video_name": video_name,
                "caption": prompt_text,
                "video_path": rel_video_path,
                "video_local_path": local_path,
                "source": source,
                "source_index": source_index,
                "source_row_index": row_idx,
                "metadata": metadata,
            }
        )

    print(
        f"[data] Unique prompts: {len(raw_prompts)}; videos to score: {len(expanded)}"
    )
    return raw_prompts, expanded


def ensure_video_local(item: dict[str, Any]) -> str:
    """Validate that the local video file exists; return its absolute path."""
    local_path = item.get("video_local_path")
    if (
        isinstance(local_path, str)
        and local_path
        and os.path.exists(local_path)
        and os.path.getsize(local_path) > 0
    ):
        return local_path
    raise FileNotFoundError(
        f"Video not found: {local_path or item.get('video_name')}"
    )