#!/usr/bin/env bash

set -euo pipefail

REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
MODE="fix"
GIT_ONLY=false

usage() {
    cat <<'EOF'
Usage: scripts/format-code.sh [--check|--fix] [--git]

Modes:
    --check   Check formatting only
    --fix     Apply formatting changes
    --git     Limit scope to staged C++ files

Defaults to formatting all C++ files in src/, include/, and tests/.
Files under tests/fixtures/ are always excluded.
EOF
}

while [[ $# -gt 0 ]]; do
    case "$1" in
        --check)
            MODE="check"
            shift
            ;;
        --fix)
            MODE="fix"
            shift
            ;;
        --git)
            GIT_ONLY=true
            shift
            ;;
        -h|--help)
            usage
            exit 0
            ;;
        *)
            printf 'Unknown option: %s\n' "$1" >&2
            usage >&2
            exit 2
            ;;
    esac
done

if [[ -n "${LLVM_BIN:-}" && -x "${LLVM_BIN}/clang-format" ]]; then
    CLANG_FORMAT="${LLVM_BIN}/clang-format"
elif command -v clang-format >/dev/null 2>&1; then
    CLANG_FORMAT="$(command -v clang-format)"
else
    printf 'clang-format not found in PATH or LLVM_BIN\n' >&2
    exit 1
fi

if [[ ! -f "$REPO_ROOT/.clang-format" ]]; then
    printf '.clang-format not found at repo root\n' >&2
    exit 1
fi

cd "$REPO_ROOT"

declare -a files=()

append_file_if_cpp() {
    local file="$1"
    [[ -f "$file" ]] || return 0
    [[ "$file" == tests/fixtures/* ]] && return 0
    case "$file" in
        src/*|include/*|tests/*)
            ;;
        *)
            return 0
            ;;
    esac
    case "$file" in
        *.c|*.cc|*.cpp|*.cxx|*.h|*.hh|*.hpp)
            files+=("$file")
            ;;
    esac
}

if [[ "$GIT_ONLY" == true ]]; then
    while IFS= read -r file; do
        [[ -n "$file" ]] || continue
        append_file_if_cpp "$file"
    done < <(git diff --cached --name-only --diff-filter=ACMR)
else
    while IFS= read -r file; do
        [[ -n "$file" ]] || continue
        files+=("$file")
    done < <(
        find src include tests \( -type f \) \
            \( -name '*.c' -o -name '*.cc' -o -name '*.cpp' -o -name '*.cxx' -o -name '*.h' -o -name '*.hh' -o -name '*.hpp' \) \
            -not -path 'tests/fixtures/*' \
            | sort
    )
fi

if [[ ${#files[@]} -eq 0 ]]; then
    printf 'No C++ files to process\n'
    exit 0
fi

if [[ "$GIT_ONLY" == true ]]; then
    deduped=()
    while IFS= read -r line; do
        [[ -n "$line" ]] && deduped+=("$line")
    done < <(printf '%s\n' "${files[@]}" | sort -u)
    files=("${deduped[@]}")
fi

failures=0
for file in "${files[@]}"; do
    if [[ "$MODE" == "check" ]]; then
        if ! "$CLANG_FORMAT" --style=file --dry-run --Werror "$file"; then
            failures=$((failures + 1))
        fi
    else
        "$CLANG_FORMAT" --style=file -i "$file"
    fi
done

if [[ "$MODE" == "check" ]]; then
    if [[ "$failures" -gt 0 ]]; then
        printf '%d file(s) need formatting\n' "$failures" >&2
        exit 1
    fi
    printf 'Formatting check passed\n'
    exit 0
fi

printf 'Formatted %d file(s)\n' "${#files[@]}"