#!/bin/bash

# Switch Stalwart between a private mail + calendar server and a real internet
# mail server, in either direction.
#
# The two ends of the switch are genuinely different jobs, and each half is
# applied by whichever layer owns it:
#
#   the app config  — which mail ports are exposed, and how. Read when the
#                     compose file is regenerated, so it needs a reinstall to
#                     reach the running container.
#   Stalwart itself — whether it should hold a publicly-trusted certificate and
#                     publish DNS. Applied live over the management API.
#
# Going public is additive and safe to repeat. Going private deliberately does
# NOT destroy anything: DKIM keys stay, the domain stays, mailboxes stay. It
# closes the doors, it does not burn the house down — which is what makes
# flipping back a setting change rather than a rebuild.

appStalwartSetMode() {
    local args="$1"
    local mode
    mode="$(authToolArg "$args" mode)"

    if [[ "$mode" != "private" && "$mode" != "public" ]]; then
        isError "Mode must be 'private' or 'public'."
        return 1
    fi

    local cfg="$(appDir stalwart)/stalwart.config"
    if [[ ! -f "$cfg" ]]; then
        isError "Stalwart does not look installed — no config at $cfg"
        return 1
    fi

    local current
    current=$(runFileOp grep -oE '^CFG_STALWART_MODE=\S*' "$cfg" 2>/dev/null | cut -d= -f2)
    if [[ "$current" == "$mode" ]]; then
        isNotice "Stalwart is already set to '$mode' — nothing to change."
        return 0
    fi

    # ---- 1. The setting itself -------------------------------------------
    runFileOp sed -i -E "s#^CFG_STALWART_MODE=.*#CFG_STALWART_MODE=${mode}#" "$cfg" 2>/dev/null
    stalwart_apply_port_access "$cfg" "$mode"
    isSuccessful "Mail exposure set to '$mode'."

    # ---- 2. What Stalwart itself has to be told --------------------------
    # Certificate management is the part that actually differs at runtime. A
    # private server has no public name to validate, so asking for a certificate
    # only produces a failing renewal loop; a public one needs the opposite.
    # Ask the server which domain it serves rather than reconstructing it from
    # install-time variables — $host_setup is populated during an install and is
    # simply absent when a tool runs on its own.
    local domain_id plan
    domain_id=$(stalwart_cli query Domain 2>/dev/null | awk 'NR==2{print $1}')

    if [[ -z "$domain_id" ]]; then
        isNotice "Could not reach Stalwart to reconfigure it — the setting is saved and"
        isNotice "  will be applied when the app is reinstalled below."
    else
        if [[ "$mode" == "private" ]]; then
            # Also drop automatic DNS: with no public role there is nothing to
            # keep in sync, and leaving a zone-write token live is blast radius
            # bought for nothing.
            plan=$(printf '{"@type":"update","object":"Domain","id":"%s","value":{"certificateManagement":{"@type":"Manual"},"dnsManagement":{"@type":"Manual"}}}' \
                "$domain_id")
        else
            # Automatic certificates need an ACME provider to point at, and a
            # server that was private has never had one — so create it here
            # rather than failing with "ACME provider not found".
            #
            # NOT FULLY VERIFIED. The private direction below is exercised end to
            # end, but this one has only ever been run against a throwaway .test
            # domain, where Let's Encrypt refuses the contact address before the
            # provider is created — so the AcmeProvider -> Domain link past that
            # point is reasoned, not observed. The plan shape is confirmed up to
            # the LE call (contact is a set, matchOn is the directory URL, an
            # acmeProviderId is required). Worth one run on a real domain.
            #
            # Two things about this are worth knowing. Creating the provider
            # REGISTERS AN ACCOUNT with Let's Encrypt there and then, so it is a
            # real outbound action, not a local setting. And the challenge type
            # is not a free choice: TLS-ALPN-01 wants port 443 and HTTP-01 wants
            # 80, both of which Traefik holds on a LibrePortal box, so DNS-01 is
            # the only one that can succeed once DNS automation is available.
            local challenge="TlsAlpn01"
            [[ "${CFG_STALWART_DNS_PROVIDER:-manual}" != "manual" && -n "${CFG_STALWART_DNS_API_TOKEN:-}" ]] \
                && challenge="Dns01"

            local domain_name contact
            domain_name=$(stalwart_cli query Domain 2>/dev/null | awk 'NR==2{print $2}')
            contact="postmaster@${domain_name}"

            # `contact` is a set, so it goes as a map of value->true, not a list.
            plan=$(printf '{"@type":"upsert","object":"AcmeProvider","matchOn":["directory"],"value":{"acme":{"directory":"https://acme-v02.api.letsencrypt.org/directory","contact":{"%s":true},"challengeType":"%s"}}}\n{"@type":"update","object":"Domain","id":"%s","value":{"certificateManagement":{"@type":"Automatic","acmeProviderId":"#acme"}}}' \
                "$contact" "$challenge" "$domain_id")

            if [[ "$challenge" == "TlsAlpn01" && -d "$(appDir traefik)" ]]; then
                isNotice "Traefik holds ports 80 and 443, so this certificate request will not"
                isNotice "  validate. Set CFG_STALWART_DNS_PROVIDER and a token to validate over"
                isNotice "  DNS instead — that is the only route that works alongside Traefik."
            fi
        fi

        if printf '%s\n' "$plan" | stalwart_cli apply --stdin >/dev/null 2>&1; then
            isSuccessful "Stalwart reconfigured for $mode operation."
        else
            isNotice "Stalwart is running but rejected the change — check it in the admin console."
        fi
    fi

    # ---- 3. Make the port change real --------------------------------------
    # No separate firewall rebuild here: the install below reallocates ports and
    # rebuilds the rules from the result. Rebuilding first would only work from
    # the old allocation and then be immediately redone.
    #
    # Port publishing lives in the compose file, which is only written from the
    # app config during an install — so without this the setting would be saved,
    # the WebUI would show the new mode, and the container would carry on
    # publishing exactly the ports it did before. A mode switch that leaves port
    # 25 open is worse than no mode switch at all.
    #
    # Safe to call from here: tools are dispatched inline rather than as their
    # own task, so this is not a nested task and cannot deadlock on the task
    # lock. It also cannot recurse — the install path calls Stalwart's install
    # hooks, and none of them call back into this tool. Provisioning inside that
    # install is a no-op too, since it skips once config.json exists.
    #
    # No --reset-network: the admin port keeps its existing random allocation,
    # so the WebUI link people have bookmarked does not move underneath them.
    echo ""
    isNotice "Applying the port changes (reinstalling the app — mail and mailboxes are kept)…"

    if ! declare -F dockerInstallApp >/dev/null 2>&1; then
        isError "Cannot reinstall automatically from here."
        isNotice "  Run it yourself to finish the switch:  libreportal app install stalwart"
        return 1
    fi

    if dockerInstallApp "stalwart" "" "false"; then
        isSuccessful "Stalwart is now running in '$mode' mode."
    else
        isError "The reinstall did not complete — the setting is saved, but the ports"
        isNotice "  have not changed yet. Retry with:  libreportal app install stalwart"
        return 1
    fi

    if [[ "$mode" == "public" ]]; then
        echo ""
        isNotice "Going public also needs, outside this box:"
        isNotice "  • outbound AND inbound port 25 (many providers block outbound by default)"
        isNotice "  • a reverse DNS (PTR) record matching ${host_setup:-your mail hostname}"
        isNotice "  • the DNS records — run the 'Show DNS Records' tool to list them"
    fi

    return 0
}