#!/usr/bin/env bash
set -euo pipefail

usage() {
  cat <<EOF
Usage: validate-structure.sh <repo-root>

Check every AGENTS.md file in a repo (root and nested) for structural
completeness against the agents.md spec's common-sections checklist
(setup/build, code style, testing, security, commit/PR conventions).
Missing individual sections are informational (not every repo needs every
section) — only an empty or entirely unfilled file is a hard failure.

Arguments:
  repo-root  Path to the repository root to scan.

Exit codes:
  0  No FAIL findings (INFO/SUGGESTION may still be printed)
  1  One or more FAIL findings
EOF
}

if [[ "${1:-}" == "--help" || "${1:-}" == "-h" ]]; then
  usage
  exit 0
fi

if [[ $# -lt 1 ]]; then
  echo "Error: repo-root is required." >&2
  echo "" >&2
  usage >&2
  exit 1
fi

python3 -u - "$1" <<'PYTHON'
import sys
import os
import re

PLACEHOLDER_RE = re.compile(r'(?i)FILL IN:|TODO:\s*write|lorem ipsum')

COMMON_SECTIONS = [
    ("setup/build commands", re.compile(r'(?im)^#{1,3}\s*(setup|install|build|getting started)')),
    ("code style", re.compile(r'(?im)^#{1,3}\s*(code style|style guide|conventions)')),
    ("testing instructions", re.compile(r'(?im)^#{1,3}\s*(test|testing)')),
    ("security considerations", re.compile(r'(?im)^#{1,3}\s*security')),
    ("commit/PR conventions", re.compile(r'(?im)^#{1,3}\s*(commit|pr|pull request)')),
]

repo_root = os.path.abspath(sys.argv[1])
if not os.path.isdir(repo_root):
    print(f"Error: '{repo_root}' is not a directory.", file=sys.stderr)
    sys.exit(1)

EXCLUDE_DIRS = {".git", "node_modules", "vendor", ".venv", "venv", "dist", "build"}

def find_agents_md(root):
    results = []
    for dirpath, dirnames, filenames in os.walk(root):
        dirnames[:] = [d for d in dirnames if d not in EXCLUDE_DIRS and not d.startswith(".")]
        for fname in filenames:
            if fname == "AGENTS.md":
                results.append(os.path.join(dirpath, fname))
    return sorted(results)

has_fail = False
file_contents = {}  # rel path -> content, for the duplication pass below

for fpath in find_agents_md(repo_root):
    rel = os.path.relpath(fpath, repo_root)
    with open(fpath, encoding="utf-8", errors="replace") as f:
        content = f.read()
    file_contents[rel] = content

    if not content.strip():
        has_fail = True
        print(f"FAIL  AGENTS.md is empty — {rel}")
        print("      Why: An empty file provides no instructions and gives agents nothing to act on.")
        print("      Fix: Add at least a project overview and setup/test commands, per the agents.md common-sections checklist.")
        print()
        continue

    if PLACEHOLDER_RE.search(content):
        has_fail = True
        print(f"FAIL  Unfilled placeholder content — {rel}")
        print("      Why: A 'FILL IN:' or template stub left in place means the file has no repo-specific instructions yet.")
        print("      Fix: Replace the placeholder with real, repo-specific content.")
        print()
        continue

    for label, pattern in COMMON_SECTIONS:
        if not pattern.search(content):
            print(f"INFO  No {label} section — {rel}")
            print(f"      Note: The agents.md common-sections checklist includes {label}; not every repo needs every section, but confirm this omission is deliberate.")
            print()

# --- Nested-vs-root duplication check ---
root_content = file_contents.get("AGENTS.md")
if root_content:
    root_lines = {ln.strip() for ln in root_content.splitlines() if ln.strip()}
    for rel, content in file_contents.items():
        if rel == "AGENTS.md":
            continue
        nested_lines = [ln.strip() for ln in content.splitlines() if ln.strip()]
        if not nested_lines:
            continue
        overlap = sum(1 for ln in nested_lines if ln in root_lines)
        ratio = overlap / len(nested_lines)
        if ratio >= 0.7:
            print(f"SUGGESTION  Nested AGENTS.md largely duplicates the root file — {rel}")
            print(f"      Why: {ratio:.0%} of this file's content lines already appear in the root AGENTS.md; per the spec's nearest-file-wins precedence, nested files don't inherit from the root, but they also shouldn't just restate it.")
            print(f"      Fix: Trim {rel} down to only what's specific to this package/directory.")
            print()

if has_fail:
    sys.exit(1)
sys.exit(0)
PYTHON