# MIT License
#
# Copyright (c) 2026 Sławomir Koszewski
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# These functions require OpenSSL to be installed on the system.
#
# SIMPLE_CA_DIR points to the root CA directory. It can be set in the environment
# before sourcing this file, or overridden per-call with --ca-dir. Once set by any
# call, subsequent calls in the same session inherit it.
#
# Directory layout:
#   $SIMPLE_CA_DIR/ca_cert.pem               — root CA certificate
#   $SIMPLE_CA_DIR/ca_key.pem                — root CA private key
#   $SIMPLE_CA_DIR/{name}_cert.pem           — certificates issued by the root CA
#   $SIMPLE_CA_DIR/{issuing_ca}/ca_cert.pem  — issuing CA certificate
#   $SIMPLE_CA_DIR/{issuing_ca}/ca_key.pem   — issuing CA private key
#   $SIMPLE_CA_DIR/{issuing_ca}/{name}_cert.pem — certificates issued by that issuing CA
#
# Certificates are always written to the directory of the CA that signs them.
# Any subdirectory containing ca_cert.pem is treated as an issuing CA.

SIMPLE_CA_DIR="${SIMPLE_CA_DIR:-}"

_rebuild_ca_bundle() {
    local BUNDLE="$SIMPLE_CA_DIR/ca_bundle.pem"
    cat "$SIMPLE_CA_DIR/ca_cert.pem" > "$BUNDLE"
    for issuing_ca_dir in $SIMPLE_CA_DIR/*; do
        if [[ -d "$issuing_ca_dir" && -f "$issuing_ca_dir/ca_cert.pem" ]]; then
            cat "$issuing_ca_dir/ca_cert.pem" >> "$BUNDLE"
        fi
    done
}

_require_ca_dir() {
    SIMPLE_CA_DIR="${SIMPLE_CA_DIR:-$(pwd)}"
    if [[ ! -d "$SIMPLE_CA_DIR" ]]; then
        echo "ERROR: CA directory '$SIMPLE_CA_DIR' does not exist." >&2
        return 1
    fi
}

_is_ip()  { [[ "$1" =~ ^[0-9]{1,3}(\.[0-9]{1,3}){3}$ ]]; }
_is_dns() { [[ "$1" =~ ^[a-z0-9-]+(\.[a-z0-9-]+)*$ ]]; }

make_ca() {
    local CA_DAYS=3650
    local ISSUING_CA=""
    local AIA_BASE_URL=""

    while [[ $# -gt 0 ]]; do
        case "$1" in
            --days)
                if [[ -z "$2" || ! "$2" =~ ^[0-9]+$ ]]; then
                    echo "ERROR: --days requires a positive integer." >&2
                    return 1
                fi
                CA_DAYS="$2"; shift 2 ;;
            --issuing-ca)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --issuing-ca requires a value." >&2
                    return 1
                fi
                if [[ "$2" == "ca" ]]; then
                    echo "ERROR: --issuing-ca cannot be 'ca'." >&2
                    return 1
                fi
                ISSUING_CA="$2"; shift 2 ;;
            --aia-base-url)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --aia-base-url requires a value." >&2
                    return 1
                fi
                AIA_BASE_URL="$2"; shift 2 ;;
            --ca-dir)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --ca-dir requires a value." >&2
                    return 1
                fi
                SIMPLE_CA_DIR="$2"; shift 2 ;;
            *) break ;;
        esac
    done

    local CA_NAME="$1"
    _require_ca_dir || return 1

    if [[ -z "$CA_NAME" ]]; then
        echo "ERROR: CA name is required." >&2
        return 1
    fi

    if [[ -z "$AIA_BASE_URL" && -f "$SIMPLE_CA_DIR/aia_base_url.txt" ]]; then
        AIA_BASE_URL="$(cat "$SIMPLE_CA_DIR/aia_base_url.txt")"
    fi

    local ROOT_CA_CERT="$SIMPLE_CA_DIR/ca_cert.pem"
    local ROOT_CA_KEY="$SIMPLE_CA_DIR/ca_key.pem"

    # Create root CA
    if [[ -z "$ISSUING_CA" ]]; then
        if [[ -f "$ROOT_CA_CERT" && -f "$ROOT_CA_KEY" ]]; then
            echo "Root CA already exists in $SIMPLE_CA_DIR, skipping."
            return 0
        fi
        echo "Generating root CA certificate '$CA_NAME' and key..."
        if ! openssl req \
            -x509 \
            -newkey rsa:4096 \
            -keyout "$ROOT_CA_KEY" \
            -out "$ROOT_CA_CERT" \
            -days "$CA_DAYS" \
            -noenc \
            -subj "/CN=${CA_NAME}" \
            -text \
            -addext "basicConstraints=critical,CA:TRUE,pathlen:1" \
            -addext "keyUsage=critical,keyCertSign,cRLSign"; then
            echo "ERROR: Failed to generate root CA certificate and key." >&2
            return 1
        fi
        _rebuild_ca_bundle
        if [[ -n "$AIA_BASE_URL" ]]; then
            echo "$AIA_BASE_URL" > "$SIMPLE_CA_DIR/aia_base_url.txt"
        fi
        return 0
    fi

    # Create issuing CA
    if [[ ! -f "$ROOT_CA_CERT" || ! -f "$ROOT_CA_KEY" ]]; then
        echo "ERROR: Cannot create issuing CA '$CA_NAME' without an existing root CA. Create the root CA first." >&2
        return 1
    fi

    local ISSUING_DIR="$SIMPLE_CA_DIR/$ISSUING_CA"
    local ISSUING_CERT="$ISSUING_DIR/ca_cert.pem"
    local ISSUING_KEY="$ISSUING_DIR/ca_key.pem"

    if [[ -f "$ISSUING_CERT" && -f "$ISSUING_KEY" ]]; then
        echo "Issuing CA '$ISSUING_CA' already exists in $ISSUING_DIR, skipping."
        return 0
    fi

    mkdir -p "$ISSUING_DIR"
    echo "Generating issuing CA certificate '$CA_NAME' and key..."
    if ! openssl req \
        -newkey rsa:4096 \
        -keyout "$ISSUING_KEY" \
        -noenc \
        -subj "/CN=${CA_NAME}" \
        -addext "basicConstraints=critical,CA:TRUE,pathlen:0" \
        -addext "keyUsage=critical,keyCertSign,cRLSign" \
        ${AIA_BASE_URL:+-addext "authorityInfoAccess=caIssuers;URI:${AIA_BASE_URL}/ca_cert.crt"} \
    | openssl x509 \
        -req \
        -CA "$ROOT_CA_CERT" \
        -CAkey "$ROOT_CA_KEY" \
        -copy_extensions copyall \
        -days "$CA_DAYS" \
        -text \
        -out "$ISSUING_CERT"; then
        echo "ERROR: Failed to generate issuing CA certificate and key." >&2
        return 1
    fi

    _rebuild_ca_bundle
    return 0
}

make_cert() {
    local ISSUING_CA=""
    local CERT_DAYS=365
    local CERT_DIR=""

    while [[ $# -gt 0 ]]; do
        case "$1" in
            --ca-dir)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --ca-dir requires a value." >&2
                    return 1
                fi
                SIMPLE_CA_DIR="$2"; shift 2 ;;
            --cert-dir)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --cert-dir requires a value." >&2
                    return 1
                fi
                CERT_DIR="$2"; shift 2 ;;
            --issuing-ca)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --issuing-ca requires a value." >&2
                    return 1
                fi
                if [[ "$2" == "ca" ]]; then
                    echo "ERROR: --issuing-ca cannot be 'ca'." >&2
                    return 1
                fi
                ISSUING_CA="$2"; shift 2 ;;
            --days)
                if [[ -z "$2" || ! "$2" =~ ^[0-9]+$ ]]; then
                    echo "ERROR: --days requires a positive integer." >&2
                    return 1
                fi
                CERT_DAYS="$2"; shift 2 ;;
            *) break ;;
        esac
    done

    local CERT_SUBJECT_NAME="$1"
    if [[ $# -gt 0 ]]; then
        shift
    fi

    _require_ca_dir || return 1

    if [[ -z "$CERT_SUBJECT_NAME" ]]; then
        echo "ERROR: Subject name is required." >&2
        return 1
    fi
    if ! _is_dns "$CERT_SUBJECT_NAME"; then
        echo "ERROR: Invalid subject name '$CERT_SUBJECT_NAME'. Must be a valid DNS name." >&2
        return 1
    fi

    local SIGNING_DIR="$SIMPLE_CA_DIR${ISSUING_CA:+/$ISSUING_CA}"
    local SIGNING_CERT="$SIGNING_DIR/ca_cert.pem"
    local SIGNING_KEY="$SIGNING_DIR/ca_key.pem"
    CERT_DIR="${CERT_DIR:-$SIGNING_DIR}"

    if [[ ! -f "$SIGNING_CERT" || ! -f "$SIGNING_KEY" ]]; then
        echo "ERROR: Signing CA certificate and key not found in $SIGNING_DIR." >&2
        return 1
    fi

    local AIA_URL=""
    if [[ -f "$SIMPLE_CA_DIR/aia_base_url.txt" ]]; then
        local BASE_URL
        BASE_URL="$(cat "$SIMPLE_CA_DIR/aia_base_url.txt")"
        AIA_URL="${BASE_URL}${ISSUING_CA:+/$ISSUING_CA}/ca_cert.crt"
    fi

    local CERT_NAME="${CERT_SUBJECT_NAME%%.*}"
    local SANS=("DNS:${CERT_SUBJECT_NAME}")

    while [[ $# -gt 0 ]]; do
        if _is_ip "$1"; then
            SANS+=("IP:$1")
        elif _is_dns "$1"; then
            SANS+=("DNS:$1")
        else
            echo "ERROR: Invalid SAN entry '$1'." >&2
            return 1
        fi
        shift
    done

    echo "Generating server certificate for '$CERT_SUBJECT_NAME' with SANs:"
    for san in "${SANS[@]}"; do echo "  - $san"; done

    if [[ -f "$CERT_DIR/${CERT_NAME}_cert.pem" && -f "$CERT_DIR/${CERT_NAME}_key.pem" ]]; then
        echo "Certificate already exists in $CERT_DIR, skipping."
        return 0
    fi

    local SANS_EXT="subjectAltName=$(IFS=,; echo "${SANS[*]}")"

    echo "Generating server certificate and key..."
    if ! openssl req \
        -newkey rsa:4096 \
        -keyout "$CERT_DIR/${CERT_NAME}_key.pem" \
        -noenc \
        -subj "/CN=${CERT_SUBJECT_NAME}" \
        -addext "basicConstraints=critical,CA:FALSE" \
        -addext "keyUsage=critical,digitalSignature,keyEncipherment" \
        -addext "extendedKeyUsage=serverAuth,clientAuth" \
        -addext "$SANS_EXT" \
        ${AIA_URL:+-addext "authorityInfoAccess=caIssuers;URI:${AIA_URL}"} \
    | openssl x509 \
        -req \
        -CA "$SIGNING_CERT" \
        -CAkey "$SIGNING_KEY" \
        -copy_extensions copyall \
        -days "$CERT_DAYS" \
        -text \
        -out "$CERT_DIR/${CERT_NAME}_cert.pem"; then
        echo "ERROR: Failed to generate server certificate and key." >&2
        return 1
    fi
}

make_pfx() {
    local ISSUING_CA=""
    local PFX_PASSWORD=""
    local APPLE_OPENSSL=0

    while [[ $# -gt 0 ]]; do
        case "$1" in
            --ca-dir)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --ca-dir requires a value." >&2
                    return 1
                fi
                SIMPLE_CA_DIR="$2"; shift 2 ;;
            --issuing-ca)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --issuing-ca requires a value." >&2
                    return 1
                fi
                if [[ "$2" == "ca" ]]; then
                    echo "ERROR: --issuing-ca cannot be 'ca'." >&2
                    return 1
                fi
                ISSUING_CA="$2"; shift 2 ;;
            --password)
                if [[ -z "$2" ]]; then
                    echo "ERROR: --password requires a value." >&2
                    return 1
                fi
                PFX_PASSWORD="$2"; shift 2 ;;
            --apple-openssl)
                APPLE_OPENSSL=1; shift ;;
            *) break ;;
        esac
    done

    local CERT_PATH="$1"
    _require_ca_dir || return 1

    if [[ -z "$CERT_PATH" ]]; then
        echo "ERROR: Certificate path is required." >&2
        return 1
    fi

    local CERT_DIR CERT_NAME KEY_PATH
    CERT_DIR="$(dirname "$CERT_PATH")"
    CERT_NAME="$(basename "$CERT_PATH" _cert.pem)"
    KEY_PATH="$CERT_DIR/${CERT_NAME}_key.pem"

    if [[ ! -d "$CERT_DIR" ]]; then
        echo "ERROR: Certificate directory '$CERT_DIR' does not exist." >&2
        return 1
    fi
    if [[ ! -f "$CERT_PATH" || ! -f "$KEY_PATH" ]]; then
        echo "ERROR: Server certificate or key not found." >&2
        return 1
    fi
    if [[ ! -f "$SIMPLE_CA_DIR/ca_cert.pem" ]]; then
        echo "ERROR: Root CA certificate not found in $SIMPLE_CA_DIR." >&2
        return 1
    fi
    if [[ -n "$ISSUING_CA" && ! -f "$SIMPLE_CA_DIR/$ISSUING_CA/ca_cert.pem" ]]; then
        echo "ERROR: Issuing CA certificate not found in $SIMPLE_CA_DIR/$ISSUING_CA." >&2
        return 1
    fi
    if [[ -f "$CERT_DIR/${CERT_NAME}.pfx" ]]; then
        echo "PKCS#12 (PFX) file already exists, aborting generation." >&2
        return 1
    fi

    PFX_PASSWORD="${PFX_PASSWORD:-changeit}"

    local OPENSSL_BIN="openssl"
    if [[ "$APPLE_OPENSSL" -eq 1 ]]; then
        OPENSSL_BIN="/usr/bin/openssl"
    fi

    echo -n "Generating PKCS#12 (PFX) file..."

    local CHAIN_FILE
    CHAIN_FILE=$(mktemp)
    trap "rm -f '$CHAIN_FILE'" EXIT QUIT KILL INT HUP

    cat "$SIMPLE_CA_DIR/ca_cert.pem" > "$CHAIN_FILE"
    if [[ -n "$ISSUING_CA" ]]; then
        cat "$SIMPLE_CA_DIR/$ISSUING_CA/ca_cert.pem" >> "$CHAIN_FILE"
    fi

    if ! "$OPENSSL_BIN" pkcs12 \
        -export \
        -out "$CERT_DIR/${CERT_NAME}.pfx" \
        -inkey "$KEY_PATH" \
        -in "$CERT_PATH" \
        -certfile "$CHAIN_FILE" \
        -password "pass:${PFX_PASSWORD}"; then
        echo "ERROR: Failed to generate PKCS#12 (PFX) file." >&2
        return 1
    fi

    echo "done."
}