#!/usr/bin/env python3
"""
collect_manuals.py - Gather all available man pages as a JSON dataset.
NixOS compatible; relies on `manpath` and `man`.
"""
import json
import os
import subprocess
import sys
from pathlib import Path

# ----------------------------------------------------------------------
# 1. Get the man page search paths
# ----------------------------------------------------------------------
def get_manpaths():
    """Return a list of directories that `man` searches for pages."""
    # On NixOS, `manpath` prints the effective MANPATH, including all profile
    # and store paths. Fall back to environment variable or hard-coded defaults.
    try:
        result = subprocess.run(["manpath", "-q"], capture_output=True, text=True, check=True)
        paths = result.stdout.strip().split(":")
        if paths and paths != [""]:
            return paths
    except (FileNotFoundError, subprocess.CalledProcessError):
        pass

    # Fallback: parse MANPATH environment variable
    manpath_env = os.environ.get("MANPATH")
    if manpath_env:
        return manpath_env.split(":")

    # Standard Linux defaults
    return ["/usr/share/man", "/usr/local/share/man"]

# ----------------------------------------------------------------------
# 2. Find all man page files
# ----------------------------------------------------------------------
def find_man_files(manpaths):
    """
    Walk each manpath directory, look inside 'man<section>' subdirs,
    and collect (topic_name, section, full_path).
    """
    # Valid extensions: compressed and raw roff
    ext_list = {".gz", ".bz2", ".xz", ".Z", ".lzma"}
    # Also accept files without compression suffix (e.g., "man1/bash.1")
    entries = []

    for base_dir in manpaths:
        base = Path(base_dir)
        if not base.is_dir():
            continue
        # All man page directories are named man1, man2, man3, manX...
        for man_dir in base.glob("man*"):
            if not man_dir.is_dir():
                continue
            # Extract section from directory name (e.g., "man1" -> "1")
            section = man_dir.name[3:]  # strip "man"
            # Find all files inside (excluding symlinks that point outside)
            for file_path in man_dir.iterdir():
                if not file_path.is_file():
                    continue
                # Resolve symlinks to avoid duplicates from different paths
                real_path = file_path.resolve()
                # Determine name by stripping the extension(s)
                name = file_path.name
                # Remove known compression extensions
                while True:
                    stem, ext = os.path.splitext(name)
                    if ext.lower() in ext_list:
                        name = stem
                    else:
                        break
                # Remove the section suffix if present (e.g., "open.2" -> "open")
                # The section suffix matches the directory section, but we remove it.
                if name.endswith(f".{section}"):
                    name = name[: -(len(section) + 1)]
                # Skip directories, etc.
                if not name:
                    continue
                entries.append((name, section, real_path))
    return entries

# ----------------------------------------------------------------------
# 3. Render a man page to plain text using `man -P cat`
# ----------------------------------------------------------------------
def render_man(topic, section, timeout=5):
    """
    Run `man -P cat <section> <topic>` and return its stdout as a string.
    Returns None on failure.
    """
    cmd = ["man", "-P", "cat", section, topic]
    try:
        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            timeout=timeout,
            # Some systems still pipe through less if MANPAGER is set;
            # environment overrides it.
            env={**os.environ, "MANPAGER": "cat", "PAGER": "cat"},
        )
        if result.returncode != 0:
            # Possibly topic not found in database but file existed; skip.
            return None
        return result.stdout
    except Exception:
        return None

# ----------------------------------------------------------------------
# 4. Main
# ----------------------------------------------------------------------
def main():
    # Collect paths
    paths = get_manpaths()
    print(f"Searching in {len(paths)} man directories...", file=sys.stderr)
    entries = find_man_files(paths)
    print(f"Found {len(entries)} manual page files.", file=sys.stderr)

    # Remove exact duplicates (same topic + section from different paths)
    # Keep the first occurrence, but we still use `man` which picks the first.
    seen = set()
    unique_entries = []
    for name, section, filepath in entries:
        key = (name, section)
        if key not in seen:
            seen.add(key)
            unique_entries.append((name, section))
    print(f"After deduplication: {len(unique_entries)} unique manuals.", file=sys.stderr)

    dataset = []
    # We'll write JSON Lines (one object per line) to avoid holding everything in memory.
    # If you prefer a single JSON array, you can collect all objects first.
    with open("manuals.jsonl", "w", encoding="utf-8") as fout:
        for idx, (name, section) in enumerate(unique_entries, 1):
            text = render_man(name, section)
            if text is None:
                # Could not render – skip or log
                continue
            record = {
                "topic": name,
                "section": section,
                "manual": text,
            }
            # Write as JSON Lines (one per line)
            fout.write(json.dumps(record, ensure_ascii=False) + "\n")

            if idx % 100 == 0:
                print(f"Processed {idx}/{len(unique_entries)}...", file=sys.stderr)

    print("Done. Output written to manuals.jsonl", file=sys.stderr)

if __name__ == "__main__":
    main()