#!/bin/bash

# Portable per-app export/import — the "one file you can hand around".
#
#   libreportal app export <app> [file]      -> <app>-<date>.lpapp
#   libreportal app import <file> [newname]
#
# WHAT THIS IS NOT
#
# Not a backup. A restic/borg/kopia repository gives you deduplication, history,
# retention and encryption; this gives you one tarball of one app at one moment.
# It exists because "email me that app" and "keep a copy before I break this" are
# real jobs that a repository answers badly — and because a single file is what
# people picture when they say "the backup file".
#
# The format is deliberately boring: gzipped tar of the app directory, with its
# .libreportal-manifest.json at the root. That manifest already records the
# compose hash, images, volumes, size, databases and storage location, so import
# gets the same reconciliation the restore preflight does, for free.
#
# The app is stopped for the duration of an export. A tar of a running Postgres
# is a corrupt Postgres, and a file that looks fine until you restore it is
# worse than a refusal.

lpAppExtension="lpapp"

appExport()
{
    local app="$1"
    local out="$2"

    if [[ -z "$app" ]]; then
        isError "Usage: app export <app_name> [file]"
        return 1
    fi

    local dir
    if ! dir=$(appDir "$app"); then
        # appDir only refuses for an unmounted location; anything else is the
        # app simply not being here, and saying "not mounted" for a typo sends
        # people looking at their disks.
        if [[ -d "$(primaryRoot)/$app" ]]; then
            isError "$app is on a storage location that is not mounted."
        else
            isError "$app is not installed."
        fi
        return 1
    fi
    if [[ ! -d "$dir" ]]; then
        isError "$app is not installed."
        return 1
    fi

    [[ -z "$out" ]] && out="$(pwd)/${app}-$(date +%Y%m%d-%H%M%S).${lpAppExtension}"
    case "$out" in */) out="${out}${app}-$(date +%Y%m%d-%H%M%S).${lpAppExtension}" ;; esac
    if [[ -e "$out" ]]; then
        isError "'$out' already exists — refusing to overwrite it."
        return 1
    fi
    # Check up front rather than failing at tar time: the error there is a bare
    # non-zero exit with no hint that the destination was the problem.
    local out_dir="${out%/*}"; [[ -z "$out_dir" ]] && out_dir="."
    if [[ ! -d "$out_dir" ]]; then
        isError "'$out_dir' does not exist."
        return 1
    fi
    if [[ ! -w "$out_dir" ]]; then
        isError "Cannot write to '$out_dir' — pick somewhere $(id -un) can write."
        return 1
    fi

    isHeader "Export $app"

    # Refresh the manifest first: it is what makes the file self-describing, and
    # a stale one would describe a different app than the tar contains.
    declare -f manifestWrite >/dev/null 2>&1 && manifestWrite "$app" >/dev/null 2>&1

    local was_running=0
    if declare -f dockerComposeDown >/dev/null 2>&1; then
        if runFileOp docker compose -f "$dir/docker-compose.yml" ps -q 2>/dev/null | grep -q .; then
            was_running=1
        fi
        isNotice "Stopping $app — a copy taken while it runs can be corrupt."
        dockerComposeDown "$app" >/dev/null 2>&1 || true
    fi

    isNotice "Writing $out"
    # Split the privileges deliberately: tar READS as the container user, because
    # app data holds sub-UIDs the manager cannot read — but it writes to STDOUT,
    # and the destination file is created by this shell, as whoever ran the
    # command. Writing directly from tar meant the container user had to be able
    # to create the file too, which fails for any normal destination.
    #
    # --numeric-owner so container uids survive the round trip rather than being
    # remapped through this machine's /etc/passwd.
    if ! runFileOp tar --numeric-owner -C "${dir%/*}" -czf - "$app" > "$out" 2>/dev/null; then
        isError "Export failed."
        rm -f "$out"
        (( was_running )) && dockerComposeUp "$app" >/dev/null 2>&1
        return 1
    fi
    chmod 0640 "$out" 2>/dev/null

    if (( was_running )); then
        isNotice "Starting $app again."
        dockerComposeUp "$app" >/dev/null 2>&1 || true
    fi

    local size; size=$(du -h "$out" 2>/dev/null | awk '{print $1}')
    isSuccessful "Exported $app to $out (${size:-?})"
    isNotice "This is a copy, not a backup — no history, no retention, and not encrypted."
    echo "$out"
}

# Read the manifest out of an export without unpacking the whole thing.
appImportManifest()
{
    local file="$1"
    tar -xzOf "$file" --wildcards '*/.libreportal-manifest.json' 2>/dev/null | head -c 65536
}

# The app name an export contains, taken from the tar's top-level directory
# rather than the filename — the filename is whatever someone renamed it to.
appImportName()
{
    local file="$1"
    tar -tzf "$file" 2>/dev/null | head -1 | cut -d/ -f1
}

# Inspect one or more exports WITHOUT importing anything, and report what would
# happen. This is what lets the WebUI ask for acceptance before it acts: the
# same checks appImport makes, run early and rendered as a list.
#
# A .lpapp is a plain tarball — not encrypted — so unlike a backup repository
# there is no password to collect, and nothing secret has to cross from the
# browser to the host. That is the whole reason this can live in the WebUI when
# the repository restore cannot.
#
# Emits one JSON object per line: {"file","app","size_bytes","verdict","detail"}
# verdict is ok | warn | refuse.
appImportCheck()
{
    local target="$1"
    if [[ -z "$target" ]]; then
        isError "Usage: app import-check <file-or-directory>"
        return 1
    fi

    local -a files=()
    if [[ -d "$target" ]]; then
        while IFS= read -r f; do [[ -n "$f" ]] && files+=("$f"); done \
            < <(find "$target" -maxdepth 1 -type f -name "*.${lpAppExtension}" 2>/dev/null | sort)
    elif [[ -f "$target" ]]; then
        files=("$target")
    else
        printf '{"file":"%s","app":"","size_bytes":0,"verdict":"refuse","detail":"No such file or directory"}\n' "$(_lpJsonStr "$target")"
        return 1
    fi

    if (( ${#files[@]} == 0 )); then
        printf '{"file":"%s","app":"","size_bytes":0,"verdict":"refuse","detail":"No .%s files found there"}\n' \
            "$(_lpJsonStr "$target")" "$lpAppExtension"
        return 1
    fi

    local f app manifest size_bytes loc dir verdict detail
    for f in "${files[@]}"; do
        verdict="ok"; detail="ready to import"
        app=$(appImportName "$f")

        if [[ -z "$app" || ! "$app" =~ ^[A-Za-z0-9._-]+$ ]]; then
            _lpImportRow "$f" "" 0 refuse "Not a LibrePortal export"
            continue
        fi

        # Squeeze whitespace first. The manifest is PRETTY-PRINTED, so the real
        # text is `"size_bytes": 1324973614` — with a space that a
        # `"key":[0-9]*` pattern does not match. Both the size and the location
        # silently came back empty, which turned the "will it fit" and "does
        # that location exist" checks into no-ops that always passed.
        manifest=$(appImportManifest "$f" | tr -d ' \n\t')
        size_bytes=$(printf '%s' "$manifest" | grep -o '"size_bytes":[0-9]*' | head -1 | cut -d: -f2)
        loc=$(printf '%s' "$manifest" | grep -o '"location":"[^"]*"' | head -1 | cut -d'"' -f4)
        [[ "$size_bytes" =~ ^[0-9]+$ ]] || size_bytes=0

        if [[ ! -f "${install_containers_dir%/}/$app/$app.config" ]]; then
            _lpImportRow "$f" "$app" "$size_bytes" refuse "This version no longer ships $app"
            continue
        fi

        if ! dir=$(appDir "$app" 2>/dev/null); then
            _lpImportRow "$f" "$app" "$size_bytes" refuse "Its storage location is not mounted"
            continue
        fi
        if [[ -d "$dir" ]]; then
            _lpImportRow "$f" "$app" "$size_bytes" refuse "$app is already installed — uninstall it first"
            continue
        fi

        if (( size_bytes > 0 )); then
            local need_kb=$(( size_bytes / 1024 )) avail_kb
            avail_kb=$(df -Pk "${dir%/*}" 2>/dev/null | awk 'NR==2 {print $4}')
            if [[ -n "$avail_kb" ]] && (( avail_kb < need_kb )); then
                _lpImportRow "$f" "$app" "$size_bytes" refuse \
                    "Needs $(( need_kb / 1048576 ))G, $(( avail_kb / 1048576 ))G free"
                continue
            fi
        fi

        if [[ -n "$loc" && "$loc" != "default" && "$loc" != "primary" ]] \
           && ! storageLocationPath "$loc" >/dev/null 2>&1; then
            verdict="warn"
            detail="came from location \"$loc\", which this machine does not have — will use $(storageLocationName "${dir%/*}")"
        fi

        _lpImportRow "$f" "$app" "$size_bytes" "$verdict" "$detail"
    done
    return 0
}

# Same check, published where the WebUI can read it. The CLI prints one JSON
# object per line (easy to pipe); the WebUI wants one document, so this wraps
# them and writes it beside the other generated data.
appImportCheckPublish()
{
    local target="$1"
    local out_dir="$(webuiDir)/frontend/data/system"
    local out_file="$out_dir/import_check.json"
    createFolders "quiet" "$sudo_user_name" "$out_dir"

    local tmp; tmp=$(mktemp) || return 1
    {
        printf '{\n  "path": "%s",\n  "checked": "%s",\n  "results": [\n' \
            "$(_lpJsonStr "$target")" "$(date -Iseconds)"
        local first=1 line
        while IFS= read -r line; do
            [[ -z "$line" ]] && continue
            (( first )) || printf ',\n'
            first=0
            printf '    %s' "$line"
        done < <(appImportCheck "$target" 2>/dev/null)
        printf '\n  ]\n}\n'
    } > "$tmp"

    runFileWrite "$out_file" < "$tmp"
    rm -f "$tmp"
    return 0
}

_lpJsonStr()
{
    local s="$1"
    s="${s//\\/\\\\}"; s="${s//\"/\\\"}"
    s="${s//$'\t'/ }"; s="${s//$'\n'/ }"; s="${s//$'\r'/}"
    printf '%s' "$s"
}

_lpImportRow()
{
    printf '{"file":"%s","app":"%s","size_bytes":%s,"verdict":"%s","detail":"%s"}\n' \
        "$(_lpJsonStr "$1")" "$(_lpJsonStr "$2")" "${3:-0}" "$4" "$(_lpJsonStr "$5")"
}

appImport()
{
    local file="$1"
    local as_name="$2"

    if [[ -z "$file" || ! -f "$file" ]]; then
        isError "Usage: app import <file.${lpAppExtension}> [new_name]"
        return 1
    fi

    isHeader "Import $file"

    local app
    app=$(appImportName "$file")
    if [[ -z "$app" || ! "$app" =~ ^[A-Za-z0-9._-]+$ ]]; then
        isError "'$file' does not look like a LibrePortal export."
        return 1
    fi
    [[ -n "$as_name" ]] && {
        isError "Importing under a different name is not supported yet — the app's config namespace (CFG_${app^^}_*) and compose identities would all need rewriting. Use 'libreportal instance create' for a second copy."
        return 1
    }

    # --- the same checks the restore preflight makes -------------------------
    local manifest size_bytes loc
    # Whitespace-squeezed: the manifest is pretty-printed (see appImportCheck).
    manifest=$(appImportManifest "$file" | tr -d ' \n\t')
    size_bytes=$(printf '%s' "$manifest" | grep -o '"size_bytes":[0-9]*' | head -1 | cut -d: -f2)
    loc=$(printf '%s' "$manifest" | grep -o '"location":"[^"]*"' | head -1 | cut -d'"' -f4)

    if [[ ! -f "${install_containers_dir%/}/$app/$app.config" ]]; then
        isError "This version of LibrePortal does not ship '$app' — it would restore into something that cannot start."
        return 1
    fi

    local dir
    if ! dir=$(appDir "$app"); then
        isError "The storage location for '$app' is not mounted."
        return 1
    fi
    if [[ -d "$dir" ]]; then
        isError "'$app' is already installed at $dir — uninstall it first, or export it before overwriting."
        return 1
    fi

    if [[ -n "$loc" && "$loc" != "default" && "$loc" != "primary" ]] \
       && ! storageLocationPath "$loc" >/dev/null 2>&1; then
        isNotice "Came from storage location '$loc', which this machine does not have — using $(storageLocationName "${dir%/*}")."
    fi

    if [[ -n "$size_bytes" && "$size_bytes" =~ ^[0-9]+$ ]]; then
        local need_kb=$(( size_bytes / 1024 )) avail_kb
        avail_kb=$(df -Pk "${dir%/*}" 2>/dev/null | awk 'NR==2 {print $4}')
        if [[ -n "$avail_kb" ]] && (( avail_kb < need_kb )); then
            isError "Needs $(( need_kb / 1048576 ))G, only $(( avail_kb / 1048576 ))G free at ${dir%/*}."
            return 1
        fi
    fi

    # --- unpack ---------------------------------------------------------------
    isNotice "Unpacking into $dir"
    runFileOp mkdir -p "${dir%/*}"
    # Mirror of the export split: the caller's shell opens the .lpapp (it may sit
    # anywhere the user can read), and tar EXTRACTS as the container user so the
    # unpacked tree lands with the right ownership. Passing the path to tar
    # instead required the container user to be able to read the file, which
    # fails for any file the user created themselves.
    if ! runFileOp tar --numeric-owner -xzf - -C "${dir%/*}" < "$file" 2>/dev/null; then
        isError "Unpack failed — removing the partial directory."
        runFileOp rm -rf "$dir"
        return 1
    fi

    # Ownership, then the normal install pipeline: the compose still carries the
    # SOURCE machine's ports, IPs and domains, and re-running the pipeline is
    # what re-allocates them for this one.
    declare -f runOwnership >/dev/null 2>&1 && runOwnership app-perms >/dev/null 2>&1

    isNotice "Wiring $app into this machine (ports, IPs, domains)."
    dockerConfigSetupToContainer "silent" "$app"
    initializeAppVariables "$app"
    declare -f migrateUrlRewrite >/dev/null 2>&1 && migrateUrlRewrite "$app" >/dev/null 2>&1
    dockerComposeUpdateAndStartApp "$app" install
    dockerComposeUp "$app"

    declare -f databaseInstallApp >/dev/null 2>&1 && databaseInstallApp "$app"

    isSuccessful "$app imported and started"
    return 0
}