from __future__ import annotations

import argparse
import difflib
import json
import tempfile
from pathlib import Path

from techviz import __version__
from techviz.document import build_context
from techviz.layout import build_layout
from techviz.prompt import build_agent_prompt
from techviz.reference_catalog import selection_payload
from techviz.renderers import render_formats
from techviz.spec import load_spec, stable_hash
from techviz.validate import has_errors, validate_spec


ROOT = Path(__file__).resolve().parents[1]
DOCUMENT = ROOT / "examples/docs/payment-flow.md"
CONTEXT = ROOT / "examples/work/payment/context.json"
PROMPT = ROOT / "examples/work/payment/prompt.md"
SPEC = ROOT / "examples/work/payment/spec.json"
ASSETS = ROOT / "examples/assets"
FORMATS = ["svg", "mermaid", "d2", "dot", "drawio", "excalidraw", "a11y"]


def _manifest(spec: object, files: list[Path]) -> str:
    payload = {
        "harness_version": __version__,
        "spec_id": spec.id,
        "spec_version": spec.version,
        "spec_sha256": stable_hash([json.dumps(spec.as_dict(), ensure_ascii=False, sort_keys=True)]),
        "source_context": spec.source_context,
        "outputs": [path.name for path in files],
        "lint_issue_count": 0,
        "assumption_count": 0,
        "assumptions_allowed": False,
        "composition_profile": spec.profile,
        "reference_ids": spec.composition.reference_ids if spec.composition else [],
        "diagram_only": bool(spec.composition.diagram_only) if spec.composition else True,
    }
    return json.dumps(payload, ensure_ascii=False, indent=2) + "\n"


def _diff(label: str, expected: str, actual: str) -> str:
    return "".join(
        difflib.unified_diff(
            expected.splitlines(keepends=True),
            actual.splitlines(keepends=True),
            fromfile=f"committed/{label}",
            tofile=f"generated/{label}",
        )
    )


def main() -> int:
    parser = argparse.ArgumentParser(description="Verify committed example artifacts are reproducible.")
    parser.add_argument("--update", action="store_true")
    args = parser.parse_args()

    # Keep the path stored in context relative and portable.
    relative_document = DOCUMENT.relative_to(ROOT)
    generated_context = build_context(relative_document, marker_id="payment-request")
    generated_context["visual_reference_candidates"] = selection_payload(generated_context, limit=5)
    context_text = json.dumps(generated_context, ensure_ascii=False, indent=2) + "\n"

    spec = load_spec(SPEC)
    issues = validate_spec(spec, generated_context)
    if has_errors(issues):
        for issue in issues:
            print(issue.as_dict())
        return 1

    prompt_text = build_agent_prompt(generated_context)

    differences: list[str] = []
    if args.update:
        CONTEXT.write_text(context_text, encoding="utf-8")
        PROMPT.write_text(prompt_text, encoding="utf-8")
    else:
        committed_context = CONTEXT.read_text(encoding="utf-8")
        if committed_context != context_text:
            differences.append(_diff(str(CONTEXT.relative_to(ROOT)), committed_context, context_text))
        committed_prompt = PROMPT.read_text(encoding="utf-8")
        if committed_prompt != prompt_text:
            differences.append(_diff(str(PROMPT.relative_to(ROOT)), committed_prompt, prompt_text))

    with tempfile.TemporaryDirectory() as tmp:
        temp_dir = Path(tmp)
        files = render_formats(spec, build_layout(spec), temp_dir, FORMATS)
        manifest_path = temp_dir / f"{spec.id}.manifest.json"
        manifest_path.write_text(_manifest(spec, files), encoding="utf-8")
        files.append(manifest_path)

        for generated in files:
            committed = ASSETS / generated.name
            if args.update:
                committed.write_bytes(generated.read_bytes())
                continue
            expected = committed.read_text(encoding="utf-8")
            actual = generated.read_text(encoding="utf-8")
            if expected != actual:
                differences.append(_diff(str(committed.relative_to(ROOT)), expected, actual))

    if differences:
        print("\n".join(differences))
        print("Generated artifacts differ. Run: PYTHONPATH=src python scripts/check_generated.py --update")
        return 1
    print("PASS committed context and diagram artifacts are reproducible")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())