#!/usr/bin/env bash
# Requires bash ≥ 4 for `mapfile`; on macOS install via `brew install bash`
# and invoke as `bash scripts/quality/license-headers.sh`.  The portable
# fallback below works on bash 3.2 too.
# scripts/quality/license-headers.sh
#
# Verify that every source file under code/ carries an SPDX-License-
# Identifier header.  The project policy (doc/release-policy.md) is:
#
#   * Every conformallab++ source file (.h, .hpp, .cpp under code/include
#     or code/src, but NOT code/deps/) must have:
#       SPDX-License-Identifier: MIT
#   * The copyright line is encouraged but not enforced (the year is
#     allowed to lag).
#
# Files under code/deps/ are vendored third-party code (Eigen, JSON,
# GLFW, libigl, …) and are skipped — they carry their own licenses.
#
# Exit codes:
#   0  every checked file has the SPDX header
#   1  at least one file is missing it
#   2  prerequisite missing
#
# Run from any directory; the script resolves the repo root from its own path.

set -euo pipefail
ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
cd "$ROOT"

SPDX="SPDX-License-Identifier: MIT"
COPYRIGHT="Copyright (c) 2024-$(date +%Y) Tarik Moussa."

FIX=0
for arg in "$@"; do
    case "$arg" in
        --fix) FIX=1 ;;
        *) echo "Unknown arg: $arg (only --fix supported)" >&2; exit 2 ;;
    esac
done

# Insert a 2-line header at the top of $1, but BELOW any existing
# `#pragma once` so the include-guard role is preserved.  Idempotent —
# the caller has already verified the SPDX line is missing.
insert_header () {
    local f="$1"
    local tmp
    tmp="$(mktemp)"
    local first_line
    first_line="$(head -1 "$f")"
    if echo "$first_line" | grep -q "^#pragma once"; then
        # Header form 1: keep `#pragma once` on line 1, then license, then blank.
        {
            echo "$first_line"
            echo "// $COPYRIGHT"
            echo "// $SPDX"
            echo
            tail -n +2 "$f"
        } > "$tmp"
    elif echo "$first_line" | grep -q "^#ifndef"; then
        # Header form 2: insert license ABOVE the include guard.
        {
            echo "// $COPYRIGHT"
            echo "// $SPDX"
            echo
            cat "$f"
        } > "$tmp"
    else
        # Other (most likely a .cpp): just prepend.
        {
            echo "// $COPYRIGHT"
            echo "// $SPDX"
            echo
            cat "$f"
        } > "$tmp"
    fi
    mv "$tmp" "$f"
}

# Files to check: code/include + code/src + code/tests.  Skip code/deps.
FILES_LIST="$(find code/include code/src code/tests \
    \( -name "*.h" -o -name "*.hpp" -o -name "*.cpp" \) \
    -type f 2>/dev/null \
    | grep -v "^code/deps/" \
    | grep -v " 2\." \
    | sort)"

n_total=0
n_missing=0
n_fixed=0
missing_list=""
while IFS= read -r f; do
    [ -z "$f" ] && continue
    n_total=$((n_total + 1))
    # Check only the first 30 lines — SPDX must be near the top.
    if ! head -30 "$f" | grep -q "$SPDX"; then
        n_missing=$((n_missing + 1))
        if [ "$FIX" -eq 1 ]; then
            insert_header "$f"
            n_fixed=$((n_fixed + 1))
        fi
        missing_list="$missing_list  $f
"
    fi
done <<EOF
$FILES_LIST
EOF

if [ "$n_total" -eq 0 ]; then
    echo "FAIL: no source files found under code/{include,src,tests}/" >&2
    exit 2
fi

echo "Checked $n_total source files for SPDX header."

if [ "$FIX" -eq 1 ]; then
    if [ "$n_fixed" -gt 0 ]; then
        echo "FIX mode: inserted '$SPDX' into $n_fixed file(s)."
        echo "          Review with: git diff"
        exit 0
    fi
fi

if [ "$n_missing" -gt 0 ]; then
    echo
    echo "FAIL: $n_missing file(s) missing '$SPDX' in their first 30 lines:"
    printf '%s' "$missing_list"
    echo
    echo "Recovery:  bash scripts/quality/license-headers.sh --fix"
    exit 1
fi

echo "OK: every checked file carries '$SPDX'."
exit 0