celery/tasks.py

"""
Art DAG Celery Tasks

Distributed rendering tasks for the Art DAG system.
"""

import hashlib
import json
import os
import subprocess
import sys
from datetime import datetime, timezone
from pathlib import Path

from celery import Task
from celery_app import app

# Add effects to path (use env var in Docker, fallback to home dir locally)
EFFECTS_PATH = Path(os.environ.get("EFFECTS_PATH", str(Path.home() / "artdag-effects")))


def get_effects_commit() -> str:
    """Get current git commit hash of effects repo."""
    try:
        result = subprocess.run(
            ["git", "rev-parse", "HEAD"],
            cwd=EFFECTS_PATH,
            capture_output=True,
            text=True
        )
        if result.returncode == 0:
            return result.stdout.strip()
    except Exception:
        pass
    return "unknown"


sys.path.insert(0, str(EFFECTS_PATH / "dog"))


def file_hash(path: Path) -> str:
    """Compute SHA3-256 hash of a file."""
    hasher = hashlib.sha3_256()
    actual_path = path.resolve() if path.is_symlink() else path
    with open(actual_path, "rb") as f:
        for chunk in iter(lambda: f.read(65536), b""):
            hasher.update(chunk)
    return hasher.hexdigest()


class RenderTask(Task):
    """Base task with provenance tracking."""

    def on_success(self, retval, task_id, args, kwargs):
        """Record successful render."""
        print(f"Task {task_id} completed: {retval}")

    def on_failure(self, exc, task_id, args, kwargs, einfo):
        """Record failed render."""
        print(f"Task {task_id} failed: {exc}")


@app.task(base=RenderTask, bind=True)
def render_effect(self, input_hash: str, effect_name: str, output_name: str) -> dict:
    """
    Render an effect on an input asset.

    Args:
        input_hash: SHA3-256 hash of input asset
        effect_name: Name of effect (e.g., "dog", "identity")
        output_name: Name for output asset

    Returns:
        Provenance record with output hash
    """
    # Cache directory (shared between server and worker)
    CACHE_DIR = Path(os.environ.get("CACHE_DIR", str(Path.home() / ".artdag" / "cache")))

    # Registry hashes (for effects/infra metadata only)
    REGISTRY = {
        "effect:dog": {
            "hash": "d048fe313433eb4e38f0e24194ffae91b896ca3e6eed3e50b2cc37b7be495555"
        },
        "effect:identity": {
            "hash": "640ea11ee881ebf4101af0a955439105ab11e763682b209e88ea08fc66e1cc03"
        },
        "infra:artdag": {
            "hash": "96a5972de216aee12ec794dcad5f9360da2e676171eabf24a46dfe1ee5fee4b0"
        },
        "infra:giles-hp": {
            "hash": "964bf6e69dc4e2493f42375013caffe26404ec3cf8eb5d9bc170cd42a361523b"
        }
    }

    # Input comes from cache by hash
    input_path = CACHE_DIR / input_hash
    if not input_path.exists():
        raise ValueError(f"Input not in cache: {input_hash}")

    output_dir = CACHE_DIR

    # Verify input
    actual_hash = file_hash(input_path)
    if actual_hash != input_hash:
        raise ValueError(f"Input hash mismatch: expected {input_hash}, got {actual_hash}")

    self.update_state(state='RENDERING', meta={'effect': effect_name, 'input': input_hash[:16]})

    # Load and apply effect
    if effect_name == "dog":
        from effect import effect_dog, DOG_HASH
        output_path = output_dir / f"{output_name}.mkv"
        result = effect_dog(input_path, output_path, {})
        expected_hash = DOG_HASH
    elif effect_name == "identity":
        from artdag.nodes.effect import effect_identity
        output_path = output_dir / f"{output_name}{input_path.suffix}"
        result = effect_identity(input_path, output_path, {})
        expected_hash = input_hash
    else:
        raise ValueError(f"Unknown effect: {effect_name}")

    # Verify output
    output_hash = file_hash(result)
    if output_hash != expected_hash:
        raise ValueError(f"Output hash mismatch: expected {expected_hash}, got {output_hash}")

    # Build effect info based on source
    if effect_name == "identity":
        # Identity is from artdag package on GitHub
        effect_info = {
            "name": f"effect:{effect_name}",
            "content_hash": REGISTRY[f"effect:{effect_name}"]["hash"],
            "repo": "github",
            "repo_url": "https://github.com/gilesbradshaw/art-dag/blob/main/artdag/nodes/effect.py"
        }
    else:
        # Other effects from rose-ash effects repo
        effects_commit = get_effects_commit()
        effect_info = {
            "name": f"effect:{effect_name}",
            "content_hash": REGISTRY[f"effect:{effect_name}"]["hash"],
            "repo": "rose-ash",
            "repo_commit": effects_commit,
            "repo_url": f"https://git.rose-ash.com/art-dag/effects/src/commit/{effects_commit}/{effect_name}"
        }

    # Build provenance
    provenance = {
        "task_id": self.request.id,
        "rendered_at": datetime.now(timezone.utc).isoformat(),
        "rendered_by": "@giles@artdag.rose-ash.com",
        "output": {
            "name": output_name,
            "content_hash": output_hash,
            "local_path": str(result)
        },
        "inputs": [
            {"content_hash": input_hash}
        ],
        "effects": [effect_info],
        "infrastructure": {
            "software": {"name": "infra:artdag", "content_hash": REGISTRY["infra:artdag"]["hash"]},
            "hardware": {"name": "infra:giles-hp", "content_hash": REGISTRY["infra:giles-hp"]["hash"]}
        }
    }

    # Save provenance
    provenance_path = result.with_suffix(".provenance.json")
    with open(provenance_path, "w") as f:
        json.dump(provenance, f, indent=2)

    return provenance


@app.task
def render_dog_from_cat() -> dict:
    """Convenience task: render cat through dog effect."""
    CAT_HASH = "33268b6e167deaf018cc538de12dbe562612b33e89a749391cef855b320a269b"
    return render_effect.delay(CAT_HASH, "dog", "dog-from-cat-celery").get()