fieldwitness/frontends/web/blueprints/attest.py

"""
Attestation blueprint — attest and verify images via Verisoo.

Wraps verisoo's attestation and verification libraries to provide:
- Image attestation: upload → hash → sign → store in append-only log
- Image verification: upload → hash → search log → display matches
- Verification receipt: same as verify but returns a downloadable JSON file
"""

from __future__ import annotations

import json
import socket
from datetime import UTC, datetime

from auth import login_required
from flask import Blueprint, Response, flash, redirect, render_template, request, url_for

bp = Blueprint("attest", __name__)


def _get_storage():
    """Get verisoo LocalStorage pointed at soosef's attestation directory."""
    from verisoo.storage import LocalStorage

    from soosef.paths import ATTESTATIONS_DIR

    return LocalStorage(base_path=ATTESTATIONS_DIR)


def _get_private_key():
    """Load the Ed25519 private key from soosef identity directory."""
    from verisoo.crypto import load_private_key

    from soosef.paths import IDENTITY_PRIVATE_KEY

    if not IDENTITY_PRIVATE_KEY.exists():
        return None
    return load_private_key(IDENTITY_PRIVATE_KEY)


def _wrap_in_chain(verisoo_record, private_key, metadata: dict | None = None):
    """Wrap a Verisoo attestation record in the hash chain.

    Returns the chain record, or None if chain is disabled.
    """
    import hashlib

    from cryptography.hazmat.primitives.serialization import load_pem_private_key

    from soosef.config import SoosefConfig
    from soosef.federation.chain import ChainStore
    from soosef.paths import CHAIN_DIR, IDENTITY_PRIVATE_KEY

    config = SoosefConfig.load()
    if not config.chain_enabled or not config.chain_auto_wrap:
        return None

    # Hash the verisoo record bytes as chain content
    record_bytes = (
        verisoo_record.to_bytes()
        if hasattr(verisoo_record, "to_bytes")
        else str(verisoo_record).encode()
    )
    content_hash = hashlib.sha256(record_bytes).digest()

    # Load Ed25519 key for chain signing (need the cryptography key, not verisoo's)
    priv_pem = IDENTITY_PRIVATE_KEY.read_bytes()
    chain_private_key = load_pem_private_key(priv_pem, password=None)

    chain_metadata = {}
    if metadata:
        if "caption" in metadata:
            chain_metadata["caption"] = metadata["caption"]
        if "location_name" in metadata:
            chain_metadata["location"] = metadata["location_name"]

    store = ChainStore(CHAIN_DIR)
    return store.append(
        content_hash=content_hash,
        content_type="verisoo/attestation-v1",
        private_key=chain_private_key,
        metadata=chain_metadata,
    )


def _allowed_image(filename: str) -> bool:
    if not filename or "." not in filename:
        return False
    return filename.rsplit(".", 1)[1].lower() in {
        "png",
        "jpg",
        "jpeg",
        "bmp",
        "gif",
        "webp",
        "tiff",
        "tif",
    }


@bp.route("/attest", methods=["GET", "POST"])
@login_required
def attest():
    """Create a provenance attestation for an image."""
    # Check identity exists
    private_key = _get_private_key()
    has_identity = private_key is not None

    if request.method == "POST":
        if not has_identity:
            flash(
                "No identity configured. Run 'soosef init' or generate one from the Keys page.",
                "error",
            )
            return redirect(url_for("attest.attest"))

        image_file = request.files.get("image")
        if not image_file or not image_file.filename:
            flash("Please select an image to attest.", "error")
            return redirect(url_for("attest.attest"))

        if not _allowed_image(image_file.filename):
            flash("Unsupported image format. Use PNG, JPG, WebP, TIFF, or BMP.", "error")
            return redirect(url_for("attest.attest"))

        try:
            image_data = image_file.read()

            # Build optional metadata
            metadata = {}
            caption = request.form.get("caption", "").strip()
            location_name = request.form.get("location_name", "").strip()
            if caption:
                metadata["caption"] = caption
            if location_name:
                metadata["location_name"] = location_name

            auto_exif = request.form.get("auto_exif", "on") == "on"

            # Create the attestation
            from verisoo.attestation import create_attestation

            attestation = create_attestation(
                image_data=image_data,
                private_key=private_key,
                metadata=metadata if metadata else None,
                auto_exif=auto_exif,
            )

            # Store in the append-only log
            storage = _get_storage()
            index = storage.append_record(attestation.record)

            # Wrap in hash chain if enabled
            chain_record = None
            try:
                chain_record = _wrap_in_chain(attestation.record, private_key, metadata)
            except Exception as e:
                import logging

                logging.getLogger(__name__).warning("Chain wrapping failed: %s", e)
                flash(
                    "Attestation saved, but chain wrapping failed. " "Check chain configuration.",
                    "warning",
                )

            # Save our own identity so we can look it up during verification
            from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat
            from verisoo.models import Identity

            pub_key = private_key.public_key()
            pub_bytes = pub_key.public_bytes(Encoding.Raw, PublicFormat.Raw)
            identity = Identity(
                public_key=pub_bytes,
                fingerprint=attestation.record.attestor_fingerprint,
                metadata={"name": "SooSeF Local Identity"},
            )
            try:
                storage.save_identity(identity)
            except Exception:
                pass  # May already exist

            record = attestation.record
            hashes = record.image_hashes

            return render_template(
                "attest/result.html",
                success=True,
                record_id=record.record_id,
                short_id=record.short_id,
                attestor=record.attestor_fingerprint,
                timestamp=record.timestamp.strftime("%Y-%m-%d %H:%M:%S UTC"),
                sha256=hashes.sha256,
                phash=hashes.phash,
                dhash=hashes.dhash,
                caption=metadata.get("caption", ""),
                location_name=metadata.get("location_name", ""),
                exif_metadata=record.metadata,
                index=index,
                filename=image_file.filename,
                chain_index=chain_record.chain_index if chain_record else None,
            )

        except Exception as e:
            flash(f"Attestation failed: {e}", "error")
            return redirect(url_for("attest.attest"))

    return render_template("attest/attest.html", has_identity=has_identity)


def _verify_image(image_data: bytes) -> dict:
    """Run the full verification pipeline against the attestation log.

    Returns a dict with keys:
        query_hashes   — ImageHashes object from verisoo
        matches        — list of match dicts (record, match_type, distances, attestor_name)
        record_count   — total records searched
    """
    from verisoo.hashing import compute_all_distances, hash_image, is_same_image

    query_hashes = hash_image(image_data)
    storage = _get_storage()
    stats = storage.get_stats()

    if stats.record_count == 0:
        return {"query_hashes": query_hashes, "matches": [], "record_count": 0}

    # Exact SHA-256 match first
    matches = []
    exact_records = storage.get_records_by_image_sha256(query_hashes.sha256)
    for record in exact_records:
        matches.append({"record": record, "match_type": "exact", "distances": {}})

    # Perceptual fallback
    if not matches and query_hashes.phash:
        all_records = [storage.get_record(i) for i in range(stats.record_count)]
        for record in all_records:
            same, match_type = is_same_image(
                query_hashes, record.image_hashes, perceptual_threshold=10
            )
            if same:
                distances = compute_all_distances(query_hashes, record.image_hashes)
                matches.append(
                    {
                        "record": record,
                        "match_type": match_type or "perceptual",
                        "distances": distances,
                    }
                )

    # Resolve attestor identities
    for match in matches:
        try:
            identity = storage.load_identity(match["record"].attestor_fingerprint)
            match["attestor_name"] = (
                identity.metadata.get("name", "Unknown") if identity else "Unknown"
            )
        except Exception:
            match["attestor_name"] = "Unknown"

    return {"query_hashes": query_hashes, "matches": matches, "record_count": stats.record_count}


@bp.route("/verify", methods=["GET", "POST"])
def verify():
    """Verify an image against attestation records.

    Intentionally unauthenticated: third parties (editors, fact-checkers, courts)
    must be able to verify provenance without having an account on this instance.
    The log read here is read-only and reveals no key material.
    """
    if request.method == "POST":
        image_file = request.files.get("image")
        if not image_file or not image_file.filename:
            flash("Please select an image to verify.", "error")
            return redirect(url_for("attest.verify"))

        if not _allowed_image(image_file.filename):
            flash("Unsupported image format.", "error")
            return redirect(url_for("attest.verify"))

        try:
            result = _verify_image(image_file.read())
            query_hashes = result["query_hashes"]
            matches = result["matches"]

            if result["record_count"] == 0:
                return render_template(
                    "attest/verify_result.html",
                    found=False,
                    message="No attestations in the local log yet.",
                    query_hashes=query_hashes,
                    filename=image_file.filename,
                    matches=[],
                )

            return render_template(
                "attest/verify_result.html",
                found=len(matches) > 0,
                message=(
                    f"Found {len(matches)} matching attestation(s)."
                    if matches
                    else "No matching attestations found."
                ),
                query_hashes=query_hashes,
                filename=image_file.filename,
                matches=matches,
            )

        except Exception as e:
            flash(f"Verification failed: {e}", "error")
            return redirect(url_for("attest.verify"))

    return render_template("attest/verify.html")


@bp.route("/verify/receipt", methods=["POST"])
def verify_receipt():
    """Return a downloadable JSON verification receipt for court or legal use.

    Accepts the same image upload as /verify. Returns a JSON file attachment
    containing image hashes, all matching attestation records with full metadata,
    the verification timestamp, and the verifier hostname.

    Intentionally unauthenticated — same access policy as /verify.
    """
    image_file = request.files.get("image")
    if not image_file or not image_file.filename:
        return Response(
            json.dumps({"error": "No image provided"}),
            status=400,
            mimetype="application/json",
        )

    if not _allowed_image(image_file.filename):
        return Response(
            json.dumps({"error": "Unsupported image format"}),
            status=400,
            mimetype="application/json",
        )

    try:
        result = _verify_image(image_file.read())
    except Exception as e:
        return Response(
            json.dumps({"error": f"Verification failed: {e}"}),
            status=500,
            mimetype="application/json",
        )

    query_hashes = result["query_hashes"]
    matches = result["matches"]
    verification_ts = datetime.now(UTC).isoformat()

    try:
        verifier_instance = socket.gethostname()
    except Exception:
        verifier_instance = "unknown"

    matching_records = []
    for match in matches:
        record = match["record"]
        rec_entry: dict = {
            "match_type": match["match_type"],
            "attestor_fingerprint": record.attestor_fingerprint,
            "attestor_name": match.get("attestor_name", "Unknown"),
            "attested_at": record.timestamp.isoformat() if record.timestamp else None,
            "record_id": str(record.record_id),
            "short_id": str(record.short_id) if hasattr(record, "short_id") else None,
        }
        # Include perceptual hash distances when present (perceptual matches only)
        if match.get("distances"):
            rec_entry["hash_distances"] = {k: int(v) for k, v in match["distances"].items()}
        # Optional fields
        if getattr(record, "captured_at", None):
            rec_entry["captured_at"] = record.captured_at.isoformat()
        if getattr(record, "location", None):
            rec_entry["location"] = record.location
        if getattr(record, "metadata", None):
            # Exclude any key material — only human-readable metadata
            safe_meta = {
                k: v
                for k, v in record.metadata.items()
                if k in ("caption", "location_name", "device", "software")
            }
            if safe_meta:
                rec_entry["metadata"] = safe_meta
        matching_records.append(rec_entry)

    receipt = {
        "schema_version": "1",
        "verification_timestamp": verification_ts,
        "verifier_instance": verifier_instance,
        "queried_filename": image_file.filename,
        "image_hash": {
            "sha256": query_hashes.sha256,
            "phash": query_hashes.phash,
            "dhash": getattr(query_hashes, "dhash", None),
        },
        "records_searched": result["record_count"],
        "matches_found": len(matching_records),
        "matching_records": matching_records,
    }

    receipt_json = json.dumps(receipt, indent=2, ensure_ascii=False)
    safe_filename = (
        image_file.filename.rsplit(".", 1)[0] if "." in image_file.filename else image_file.filename
    )
    download_name = f"receipt_{safe_filename}_{datetime.now(UTC).strftime('%Y%m%dT%H%M%SZ')}.json"

    return Response(
        receipt_json,
        status=200,
        mimetype="application/json",
        headers={"Content-Disposition": f'attachment; filename="{download_name}"'},
    )


@bp.route("/attest/log")
@login_required
def log():
    """List recent attestations."""
    try:
        storage = _get_storage()
        stats = storage.get_stats()
        records = []
        # Show last 50 records, newest first
        start = max(0, stats.record_count - 50)
        for i in range(stats.record_count - 1, start - 1, -1):
            try:
                record = storage.get_record(i)
                records.append({"index": i, "record": record})
            except Exception:
                continue
        return render_template("attest/log.html", records=records, total=stats.record_count)
    except Exception as e:
        flash(f"Could not read attestation log: {e}", "error")
        return render_template("attest/log.html", records=[], total=0)