#!/usr/bin/env python3
"""
AI_Visualizer agent.

Generates placeholder PlantUML diagrams on demand when @AI_Visualizer (or @AI_visual)
is mentioned in a discussion. Provides scaffolding for future AI-powered
diagram generation.
"""

from __future__ import annotations

import argparse
import re
from pathlib import Path

# Support multiple mention patterns (case-insensitive)
MENTION_REGEX = re.compile(r"@ai[-_]visual(?:izer)?\s*:?\s*(.+)", re.IGNORECASE)
BLOCK_START = "<!-- AUTO:VISUALIZER START -->"
BLOCK_END = "<!-- AUTO:VISUALIZER END -->"


def find_next_diagram(diagram_dir: Path) -> Path:
    diagram_dir.mkdir(parents=True, exist_ok=True)
    existing = sorted(diagram_dir.glob("diagram_*.puml"))
    next_index = len(existing) + 1
    return diagram_dir / f"diagram_{next_index:03d}.puml"


def write_placeholder_plantuml(path: Path, prompt: str) -> None:
    content = "\n".join(
        [
            "@startuml",
            "' Auto-generated scaffold",
            "' Requested via @AI_Visualizer",
            f"note as N1",
            prompt.strip() or "Diagram requested with no additional context.",
            "end note",
            "@enduml",
            "",
        ]
    )
    path.write_text(content, encoding="utf-8")


def append_comment(discussion_path: Path, diagram_rel: Path) -> None:
    comment = (
        f"{BLOCK_START}\n"
        "Name: AI_Visualizer\n"
        f"Generated diagram: `{diagram_rel.as_posix()}`\n"
        "\n"
        "Let me know if you need an updated view.\n"
        f"{BLOCK_END}\n"
    )
    text = discussion_path.read_text(encoding="utf-8")
    if text and not text.endswith("\n"):
        text += "\n"
    discussion_path.write_text(text + comment, encoding="utf-8")


def main() -> int:
    parser = argparse.ArgumentParser(description="AI Visualizer agent")
    parser.add_argument("--repo-root", required=True, help="Repository root path")
    parser.add_argument("--path", required=True, help="Relative path to discussion file")
    args = parser.parse_args()

    repo_root = Path(args.repo_root).resolve()
    discussion_rel = Path(args.path)
    discussion_path = (repo_root / discussion_rel).resolve()

    if not discussion_path.exists():
        return 0

    text = discussion_path.read_text(encoding="utf-8")
    match = MENTION_REGEX.search(text)
    if not match:
        return 0

    # Simple check to avoid re-processing if our comment is already there
    if f"Name: AI_Visualizer" in text and BLOCK_START in text:
        return 0

    diagram_dir = discussion_path.parent.parent / "diagrams"
    diagram_path = find_next_diagram(diagram_dir)
    prompt = match.group(1)  # Extract text after the mention
    write_placeholder_plantuml(diagram_path, prompt)
    append_comment(discussion_path, diagram_path.relative_to(repo_root))
    return 0


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