server.py

"""
DataView — General-purpose dataset visualizer for HuggingFace-style files.
Supports: Parquet, Arrow, CSV, JSON/JSONL.
Run:  python tools/dataview/server.py [--port 8080] [--dir /path/to/datasets]
"""

import argparse
import io
import json
import os
import uuid
from pathlib import Path
from typing import Any

import pandas as pd
import pyarrow as pa
import pyarrow.parquet as pq
from fastapi import FastAPI, HTTPException, Query
from fastapi.responses import HTMLResponse, Response
from fastapi.staticfiles import StaticFiles
from PIL import Image

app = FastAPI(title="DataView")

STATIC_DIR = Path(__file__).parent / "static"
app.mount("/static", StaticFiles(directory=str(STATIC_DIR)), name="static")

DEFAULT_DIR = str(Path(__file__).parent.parent.parent)

# ---------------------------------------------------------------------------
# In-memory store of opened files
# ---------------------------------------------------------------------------
_store: dict[str, dict] = {}  # file_id -> metadata

SUPPORTED_EXTS = {".parquet", ".pq", ".arrow", ".feather", ".csv", ".tsv", ".json", ".jsonl"}


def _detect_format(path: str) -> str:
    p = path.lower()
    if p.endswith(".parquet") or p.endswith(".pq"):
        return "parquet"
    if p.endswith(".arrow") or p.endswith(".feather"):
        return "arrow"
    if p.endswith(".csv") or p.endswith(".tsv"):
        return "csv"
    if p.endswith(".jsonl") or p.endswith(".json"):
        return "jsonl" if ".jsonl" in p else "json"
    return "unknown"


def _read_parquet_schema(path: str) -> dict:
    pf = pq.ParquetFile(path)
    schema = pf.schema_arrow
    meta = pf.metadata
    return {
        "format": "parquet",
        "num_rows": meta.num_rows,
        "num_row_groups": meta.num_row_groups,
        "file_size_bytes": os.path.getsize(path),
        "columns": [
            {
                "name": field.name,
                "type": str(field.type),
                "is_image": str(field.type) in ("binary", "large_binary"),
                "nullable": field.nullable,
            }
            for field in schema
        ],
    }


def _read_arrow_schema(path: str) -> dict:
    table = pa.ipc.open_file(path).read_all()
    return {
        "format": "arrow",
        "num_rows": table.num_rows,
        "columns": [
            {
                "name": field.name,
                "type": str(field.type),
                "is_image": str(field.type) in ("binary", "large_binary"),
                "nullable": field.nullable,
            }
            for field in table.schema
        ],
    }


def _read_csv_schema(path: str) -> dict:
    df = pd.read_csv(path, nrows=0)
    return {
        "format": "csv",
        "num_rows": sum(1 for _ in open(path)) - 1,
        "columns": [
            {
                "name": col,
                "type": str(dtype),
                "is_image": False,
                "nullable": True,
            }
            for col, dtype in df.dtypes.items()
        ],
    }


def _read_json_schema(path: str) -> dict:
    with open(path) as f:
        first_line = f.readline().strip()
    if first_line.startswith("["):
        rows = json.loads(open(path).read())
        num_rows = len(rows)
        sample = rows[0] if rows else {}
    else:
        num_rows = sum(1 for _ in open(path))
        sample = json.loads(first_line) if first_line else {}
    return {
        "format": "json",
        "num_rows": num_rows,
        "columns": [
            {
                "name": k,
                "type": type(v).__name__,
                "is_image": isinstance(v, bytes),
                "nullable": v is None,
            }
            for k, v in sample.items()
        ],
    }


# ---------------------------------------------------------------------------
# Routes
# ---------------------------------------------------------------------------
@app.get("/", response_class=HTMLResponse)
async def index():
    return (STATIC_DIR / "index.html").read_text()


@app.get("/api/browse")
async def browse(path: str = Query(""), show_hidden: bool = Query(False)):
    """List directory contents for the folder browser."""
    if not path:
        path = DEFAULT_DIR
    path = os.path.expanduser(path)

    if not os.path.isdir(path):
        raise HTTPException(400, f"Not a directory: {path}")

    entries = []
    try:
        for name in sorted(os.listdir(path)):
            if not show_hidden and name.startswith("."):
                continue
            full = os.path.join(path, name)
            is_dir = os.path.isdir(full)
            ext = os.path.splitext(name)[1].lower() if not is_dir else ""
            size = 0
            if not is_dir:
                try:
                    size = os.path.getsize(full)
                except OSError:
                    pass
            entries.append({
                "name": name,
                "path": full,
                "is_dir": is_dir,
                "ext": ext,
                "is_dataset": ext in SUPPORTED_EXTS,
                "size": size,
            })

        # Sort: dirs first, then dataset files, then others
        def sort_key(e):
            if e["is_dir"]:
                return (0, e["name"].lower())
            if e["is_dataset"]:
                return (1, e["name"].lower())
            return (2, e["name"].lower())

        entries.sort(key=sort_key)
    except PermissionError:
        raise HTTPException(403, f"Permission denied: {path}")

    return {
        "path": path,
        "parent": os.path.dirname(path) if path != "/" else None,
        "entries": entries,
    }


@app.get("/api/default-path")
async def default_path():
    return {"path": DEFAULT_DIR}


@app.post("/api/open")
async def open_file(body: dict):
    path = body.get("path", "").strip()
    if not path:
        raise HTTPException(400, "path is required")
    path = os.path.expanduser(path)
    if not os.path.isfile(path):
        raise HTTPException(404, f"File not found: {path}")

    fmt = _detect_format(path)
    try:
        if fmt == "parquet":
            info = _read_parquet_schema(path)
        elif fmt == "arrow":
            info = _read_arrow_schema(path)
        elif fmt == "csv":
            info = _read_csv_schema(path)
        elif fmt in ("json", "jsonl"):
            info = _read_json_schema(path)
        else:
            raise HTTPException(400, f"Unsupported format: {fmt}")
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(500, f"Error reading file: {e}")

    fid = str(uuid.uuid4())[:8]
    _store[fid] = {"path": path, "fmt": fmt, "info": info}
    return {"id": fid, **info, "path": path}


@app.get("/api/data/{fid}")
async def get_data(
    fid: str,
    offset: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=500),
    columns: str = Query("", description="comma-separated column names, empty=all"),
):
    if fid not in _store:
        raise HTTPException(404, "File not opened")
    entry = _store[fid]
    path, fmt = entry["path"], entry["fmt"]
    col_list = [c.strip() for c in columns.split(",") if c.strip()] or None

    try:
        if fmt == "parquet":
            table = pq.read_table(path, columns=col_list)
            df = table.to_pandas()
        elif fmt == "arrow":
            table = pa.ipc.open_file(path).read_all()
            if col_list:
                table = table.select(col_list)
            df = table.to_pandas()
        elif fmt == "csv":
            df = pd.read_csv(path, usecols=col_list)
        elif fmt in ("json", "jsonl"):
            if fmt == "jsonl":
                df = pd.read_json(path, lines=True)
            else:
                df = pd.read_json(path)
            if col_list:
                df = df[col_list]
        else:
            raise HTTPException(400, "Unsupported format")
    except Exception as e:
        raise HTTPException(500, str(e))

    total = len(df)
    sliced = df.iloc[offset : offset + limit]

    # Serialize: handle binary columns by converting to base64 placeholders
    records = []
    for _, row in sliced.iterrows():
        rec = {}
        for col in df.columns:
            val = row[col]
            if isinstance(val, bytes):
                rec[col] = {"_type": "image", "size": len(val)}
            elif pd.isna(val):
                rec[col] = None
            elif hasattr(val, "item"):
                rec[col] = val.item()
            else:
                rec[col] = val
        records.append(rec)

    return {"total": total, "offset": offset, "limit": limit, "data": records}


@app.get("/api/image/{fid}/{row}/{col}")
async def get_image(fid: str, row: int, col: str):
    if fid not in _store:
        raise HTTPException(404, "File not opened")
    entry = _store[fid]
    path, fmt = entry["path"], entry["fmt"]

    try:
        if fmt == "parquet":
            table = pq.read_table(path, columns=[col])
        elif fmt == "arrow":
            table = pa.ipc.open_file(path).read_all().select([col])
        else:
            raise HTTPException(400, "Image columns only supported for parquet/arrow")

        if row >= table.num_rows:
            raise HTTPException(400, "Row index out of range")

        cell = table.column(col)[row].as_py()
        if not isinstance(cell, (bytes, bytearray)):
            raise HTTPException(400, "Column is not binary/image")

        img = Image.open(io.BytesIO(cell))
        buf = io.BytesIO()
        img.save(buf, format="WEBP", quality=85)
        return Response(content=buf.getvalue(), media_type="image/webp")
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(500, str(e))


@app.get("/api/stats/{fid}")
async def get_stats(fid: str):
    if fid not in _store:
        raise HTTPException(404, "File not opened")
    entry = _store[fid]
    path, fmt = entry["path"], entry["fmt"]
    info = entry["info"]

    try:
        if fmt == "parquet":
            table = pq.read_table(path)
            df = table.to_pandas()
        elif fmt == "arrow":
            table = pa.ipc.open_file(path).read_all()
            df = table.to_pandas()
        elif fmt == "csv":
            df = pd.read_csv(path)
        elif fmt in ("json", "jsonl"):
            df = pd.read_json(path, lines=(fmt == "jsonl"))
        else:
            raise HTTPException(400, "Unsupported format")
    except Exception as e:
        raise HTTPException(500, str(e))

    stats = []
    for col_info in info["columns"]:
        name = col_info["name"]
        is_img = col_info["is_image"]
        col = df[name]

        non_null = int(col.notna().sum())
        null_count = int(col.isna().sum())

        s: dict[str, Any] = {
            "name": name,
            "type": col_info["type"],
            "non_null": non_null,
            "null_count": null_count,
        }

        if is_img:
            sizes = col.dropna().apply(lambda x: len(x) if isinstance(x, (bytes, bytearray)) else 0)
            if len(sizes) > 0:
                s["image_stats"] = {
                    "min_bytes": int(sizes.min()),
                    "max_bytes": int(sizes.max()),
                    "mean_bytes": float(sizes.mean()),
                }
        elif col.dtype in ("int64", "float64", "int32", "float32"):
            s["numeric_stats"] = {
                "min": float(col.min()) if non_null else None,
                "max": float(col.max()) if non_null else None,
                "mean": float(col.mean()) if non_null else None,
                "median": float(col.median()) if non_null else None,
                "std": float(col.std()) if non_null else None,
            }
        elif col.dtype == "object":
            nunique = int(col.nunique())
            s["text_stats"] = {
                "nunique": nunique,
                "avg_length": float(col.astype(str).str.len().mean()) if non_null else 0,
            }
            if nunique <= 30:
                vc = col.value_counts().head(20)
                s["text_stats"]["top_values"] = {str(k): int(v) for k, v in vc.items()}
        elif col.dtype == "bool":
            vc = col.value_counts()
            s["bool_stats"] = {str(k): int(v) for k, v in vc.items()}

        stats.append(s)

    return {"total_rows": len(df), "columns": stats}


@app.get("/api/list")
async def list_files():
    return [
        {"id": fid, "path": e["path"], "format": e["fmt"], "rows": e["info"]["num_rows"]}
        for fid, e in _store.items()
    ]


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="DataView server")
    parser.add_argument("--port", type=int, default=8080)
    parser.add_argument("--host", default="0.0.0.0")
    parser.add_argument("--dir", default=None, help="Default directory for folder browser")
    args = parser.parse_args()

    if args.dir:
        DEFAULT_DIR = os.path.expanduser(args.dir)

    import uvicorn
    print(f"\n  DataView running at http://localhost:{args.port}")
    print(f"  Default directory: {DEFAULT_DIR}\n")
    uvicorn.run(app, host=args.host, port=args.port, log_level="info")