check-swift-headers.sh

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

# Swift Header Checker / Fixer
#
# - Verifies that Swift source files contain a standardized header
# - Can optionally fix or insert headers in-place (--fix)
# - Uses git to determine file creation dates where possible
# - Supports excluding files via .swiftheaderignore
#
# Intended usage:
#   - CI: fail if headers are missing or malformed
#   - Local: optionally auto-fix headers

# Logging helpers (stderr, consistent formatting)
log() { printf -- "** %s\n" "$*" >&2; }
error() { printf -- "** ERROR: %s\n" "$*" >&2; }
fatal() {
    error "$@"
    exit 1
}

# Configuration / state
DEFAULT_AUTHOR="Binary Birds"
FIX_MODE=0
HAS_ERRORS=0

# Argument parsing
while [ $# -gt 0 ]; do
    case "$1" in
        --fix)
            FIX_MODE=1
            ;;
        --author)
            shift
            [ -z "${1:-}" ] && fatal "--author requires a value"
            DEFAULT_AUTHOR="$1"
            ;;
        *)
            fatal "Unknown argument: $1"
            ;;
    esac
    shift
done

if [ "$FIX_MODE" -eq 1 ]; then
    log "Fix mode enabled — headers will be inserted or corrected."
else
    log "Checking Swift file headers..."
fi

# Project name
PROJECT_NAME="$(basename "$PWD")"

# Date helpers
normalize_date() {
    local raw="$1"
    if command -v gdate >/dev/null 2>&1; then
        gdate -d "$raw" +"%Y. %m. %d" 2>/dev/null
    else
        date -d "$raw" +"%Y. %m. %d" 2>/dev/null
    fi
}

get_file_creation_date() {
    local file="$1"
    if git ls-files --error-unmatch "$file" >/dev/null 2>&1; then
        git log -1 --format="%ad" --date=format:"%Y. %m. %d" -- "$file"
    else
        date +"%Y. %m. %d"
    fi
}

# Header detection helpers

# Find the line number of the "Created by" line (header anchor)
find_header_line() {
    grep -nE '^//  Created by .+ on [0-9]{4}\. [0-9]{2}\. [0-9]{2}\.{1,2}$' "$1" |
        head -n1 |
        cut -d: -f1
}

# Validate header structure relative to the anchor line
is_header_valid_at_line() {
    local file="$1"
    local line="$2"
    local filename
    filename=$(basename "$file")

    sed -n "$((line - 4)),${line}p" "$file" | awk -v f="$filename" -v p="$PROJECT_NAME" '
    NR==1 && $0=="//" {next}
    NR==2 && $0=="//  " f {next}
    NR==3 && $0=="//  " p {next}
    NR==4 && $0=="//" {next}
    NR==5 && $0 ~ "^//  Created by .+ on [0-9]{4}\\. [0-9]{2}\\. [0-9]{2}\\.\\.{0,1}$" {exit 0}
    {exit 1}
  '
}

extract_author_from_header_line() {
    sed -E 's|^//  Created by (.+) on [0-9]{4}\. [0-9]{2}\. [0-9]{2}\.{1,2}$|\1|'
}

extract_date_from_header_line() {
    sed -E 's|^//  Created by .+ on ([0-9]{4}\. [0-9]{2}\. [0-9]{2})\.{1,2}$|\1|'
}

# Returns 0 when the header line uses legacy double-dot suffix.
is_legacy_double_dot_header_line() {
    [[ "$1" =~ \.\.$ ]]
}

# Replace an invalid header block in place
replace_header_at_line() {
    local file="$1"
    local line="$2"
    local tmpfile
    tmpfile=$(mktemp)

    # Extract original author and date
    local header_line
    header_line=$(sed -n "${line}p" "$file")

    local author
    author=$(printf '%s\n' "$header_line" | extract_author_from_header_line)

    local date
    date=$(printf '%s\n' "$header_line" | extract_date_from_header_line)

    # Safety fallback (should never happen)
    [ -z "$author" ] && author="$DEFAULT_AUTHOR"
    [ -z "$date" ] && date="$(get_file_creation_date "$file")"

    # Remove the old header block
    local start=$((line - 4))
    [ "$start" -lt 1 ] && start=1
    sed "${start},${line}d" "$file" >"$tmpfile"

    # Rebuild file WITHOUT adding extra blank lines
    {
        echo "//"
        echo "//  $(basename "$file")"
        echo "//  $PROJECT_NAME"
        echo "//"
        echo "//  Created by $author on $date."
        cat "$tmpfile"
    } >"$tmpfile.fixed"

    mv "$tmpfile.fixed" "$file"
}

# Header validation / fixing
check_or_fix_header() {
    local file="$1"
    local filename
    filename=$(basename "$file")

    # Explicitly ignore Package.swift
    [ "$filename" = "Package.swift" ] && return 0

    local header_line
    header_line=$(find_header_line "$file" || true)

    if [ -n "$header_line" ]; then
        if is_header_valid_at_line "$file" "$header_line"; then
            if [ "$FIX_MODE" -eq 1 ]; then
                local header_text
                header_text=$(sed -n "${header_line}p" "$file")
                if is_legacy_double_dot_header_line "$header_text"; then
                    replace_header_at_line "$file" "$header_line"
                    log "Normalized legacy header: $file"
                fi
            fi
            return 0
        fi

        if [ "$FIX_MODE" -eq 1 ]; then
            replace_header_at_line "$file" "$header_line"
            log "Fixed header: $file"
        else
            error "❌ $file - Header is invalid"
            return 1
        fi
    else
        # No header anywhere → insert at top
        if [ "$FIX_MODE" -eq 1 ]; then
            local tmpfile
            tmpfile=$(mktemp)
            {
                echo "//"
                echo "//  $filename"
                echo "//  $PROJECT_NAME"
                echo "//"
                echo "//  Created by $DEFAULT_AUTHOR on $(get_file_creation_date "$file")."
                echo ""
                cat "$file"
            } >"$tmpfile"
            mv "$tmpfile" "$file"
            log "Header added: $file"
        else
            error "❌ $file - Header missing"
            return 1
        fi
    fi
}

# Exclusions
IGNORE_FILE=".swiftheaderignore"
EXCLUDE_PATTERNS=()

if [ -f "$IGNORE_FILE" ]; then
    log "Using exclusion list from $IGNORE_FILE"
    while IFS= read -r line || [ -n "$line" ]; do
        [[ -n "$line" && ! "$line" =~ ^# ]] && EXCLUDE_PATTERNS+=(":(exclude)$line")
    done <"$IGNORE_FILE"
else
    EXCLUDE_PATTERNS+=(
        ":(exclude).*"
        ":(exclude)*.txt"
        ":(exclude)*.png"
        ":(exclude)*.jpeg"
        ":(exclude)*.jpg"
        ":(exclude)*.sh"
        ":(exclude)*.html"
        ":(exclude)*.yaml"
        ":(exclude)README.md"
        ":(exclude)Package.resolved"
        ":(exclude)Makefile"
        ":(exclude)LICENSE"
        ":(exclude)Package*.swift"
        ":(exclude)docker/**"
    )
fi

# File processing
FILES=()
while IFS= read -r -d '' file; do
    FILES+=("$file")
done < <(git ls-files -z --cached --others --exclude-standard "${EXCLUDE_PATTERNS[@]}")

for file in "${FILES[@]}"; do
    if ! check_or_fix_header "$file"; then
        HAS_ERRORS=1
    fi
done

# Final result
if [ "$HAS_ERRORS" -eq 1 ]; then
    if [ "$FIX_MODE" -eq 1 ]; then
        log "⚠️ Some headers were fixed."
    else
        fatal "Some files have header issues."
    fi
else
    if [ "$FIX_MODE" -eq 1 ]; then
        log "✅ Headers updated successfully."
    else
        log "✅ All headers are valid."
    fi
fi