from __future__ import annotations
import httpx, hashlib, json, os, mimetypes
from datetime import datetime
from pydantic import HttpUrl
from .models import SourceMeta

def _sha256_bytes(b: bytes) -> str:
    return hashlib.sha256(b).hexdigest()

def fetch_url(url: str, out_dir: str = "data") -> str:
    os.makedirs(out_dir, exist_ok=True)
    ts = datetime.utcnow().strftime("%Y%m%dT%H%M%SZ")
    filename_base = url.replace("://", "_").replace("/", "_")
    target_path = os.path.join(out_dir, f"{filename_base}")
    manifest_path = target_path + ".json"

    with httpx.Client(follow_redirects=True, timeout=60) as client:
        r = client.get(url)
        r.raise_for_status()
        media_type = r.headers.get("content-type", "").split(";")[0] or mimetypes.guess_type(url)[0] or "application/octet-stream"
        b = r.content
        sha = _sha256_bytes(b)
        # write raw artifact
        ext = mimetypes.guess_extension(media_type) or ".bin"
        artifact_path = target_path + ext
        with open(artifact_path, "wb") as f:
            f.write(b)
        # write manifest
        meta = {
            "url": url,
            "retrieved_at": ts,
            "status_code": r.status_code,
            "redirect_chain": [str(h.request.url) for h in r.history] + [str(r.request.url)],
            "etag": r.headers.get("etag"),
            "last_modified": r.headers.get("last-modified"),
            "media_type": media_type,
            "sha256": sha,
            "bytes": len(b),
            "artifact_path": artifact_path,
        }
        with open(manifest_path, "w") as f:
            json.dump(meta, f, indent=2)
    return manifest_path

def manifest_to_source(meta_path: str, title: str | None = None, jurisdiction: str = "OTHER") -> SourceMeta:
    with open(meta_path) as f:
        m = json.load(f)
    return SourceMeta(
        jurisdiction=jurisdiction, title=title, url=m["url"],
        media_type=m["media_type"], etag=m.get("etag"), last_modified=m.get("last_modified"),
        sha256=m.get("sha256")
    )