#!/usr/bin/env bash
# Prepend SPDX license identifiers to every Rust and Lua source file.
# Idempotent: files already containing an `SPDX-License-Identifier:` line are skipped.
# Run from the repository root: `./tools/add-license-headers.sh`

set -euo pipefail

readonly LICENSE_ID="AGPL-3.0-only"
readonly RUST_HEADER="// SPDX-License-Identifier: ${LICENSE_ID}"
readonly LUA_HEADER="-- SPDX-License-Identifier: ${LICENSE_ID}"

# Directories to scan, relative to the repository root.
readonly RUST_DIRS=("crates")
readonly LUA_DIRS=("assets/scripts" "mods")

added=0
skipped=0

prepend_if_missing() {
    local file="$1"
    local header="$2"

    if grep -q "SPDX-License-Identifier:" "$file"; then
        skipped=$((skipped + 1))
        return
    fi

    # Use a temp file in the same directory so the rename is atomic on the same filesystem.
    local tmp
    tmp=$(mktemp "${file}.XXXXXX")
    {
        printf '%s\n\n' "$header"
        cat "$file"
    } >"$tmp"
    mv "$tmp" "$file"
    added=$((added + 1))
}

scan_dir() {
    local dir="$1"
    local ext="$2"
    local header="$3"

    [[ -d "$dir" ]] || return 0

    while IFS= read -r -d '' file; do
        prepend_if_missing "$file" "$header"
    done < <(find "$dir" -type f -name "*.${ext}" -print0)
}

for dir in "${RUST_DIRS[@]}"; do
    scan_dir "$dir" "rs" "$RUST_HEADER"
done

for dir in "${LUA_DIRS[@]}"; do
    scan_dir "$dir" "lua" "$LUA_HEADER"
done

printf 'License headers added: %d, already present: %d\n' "$added" "$skipped"