#!/bin/bash

# Choosing which drive an app is installed onto.
#
# The resolver already supported this — CFG_<APP>_STORAGE names a location and
# appDir sends data, compose and config there — and every app template ships the
# field with a generated dropdown of the registered locations. What was missing
# was making the choice effective AT INSTALL TIME. Until now the only routes
# were editing the config by hand before installing, or installing onto the
# default disk and then `app move`ing it, which copies the data twice.
#
# The choice arrives two ways, and they are the same choice:
#
#   libreportal app install <app> --storage=<name>     -> LP_INSTALL_STORAGE
#   the storage dropdown in the App Center install form -> config_variables
#
# Both are resolved to one answer here so there is a single code path.
#
# ORDERING is the whole difficulty. installApp does:
#
#   1. dockerConfigSetupToContainer silent <app>     creates the app dir at
#                                                    appDir() and copies the
#                                                    template config into it
#   2. initializeAppVariables                        sources that config
#   ...
#   3. dockerConfigSetupToContainer loud <app> install <config_variables>
#                                                    applies the form overrides
#
# The choice has to be live before (1) or the directory is created on the wrong
# disk; written into the config between (1) and (2) or sourcing the fresh
# template resets it to "default" and every later appDir in the same process
# returns the primary root; and present in config_variables for (3) or that
# pass writes "default" back over it. Miss any one and you get an app whose
# directory and config disagree — which resolves correctly only for as long as
# nothing sources the config.

# The requested location, or empty for "no opinion" (the normal path).
# The CLI flag wins over the form field when both are present.
storageChoiceFor()
{
    local app="$1" config_vars="${2:-}"
    [[ -n "$app" ]] || return 0

    if [[ -n "${LP_INSTALL_STORAGE:-}" ]]; then
        printf '%s' "$LP_INSTALL_STORAGE"
        return 0
    fi

    local key="CFG_${app^^}_STORAGE" pair
    local -a pairs=()
    IFS='|' read -ra pairs <<< "$config_vars"
    for pair in "${pairs[@]}"; do
        if [[ "$pair" == "$key="* ]]; then
            printf '%s' "${pair#$key=}"
            return 0
        fi
    done
    return 0
}

# Make appDir resolve to the chosen location, before anything is created.
storagePlaceAppPre()
{
    local app="$1" want="$2"
    [[ -n "$app" && -n "$want" ]] || return 0
    # "default" is the templates' own value and means "follow CFG_STORAGE_DEFAULT",
    # so it is not a placement and must not be treated as one.
    [[ "$want" == "default" ]] && return 0

    # Some apps are deliberately fixed to the primary root because other apps
    # reach them by literal path; their template marks the field **READONLY**.
    # storageMoveApp already refuses to move those, and installing one somewhere
    # else is the same violation arrived at from the other end — it just breaks
    # the referring app immediately instead of later.
    local tmpl="${install_containers_dir%/}/$app/$app.config"
    if [[ -f "$tmpl" ]] && grep -qE "^CFG_${app^^}_STORAGE=.*\*\*READONLY\*\*" "$tmpl" 2>/dev/null; then
        isError "$app is fixed to the default location — other apps reference it by path."
        isNotice "Install it without a location, or move the apps that depend on it instead."
        return 1
    fi

    local root
    if [[ "$want" == "primary" ]]; then
        root=$(primaryRoot)
    elif ! root=$(storageLocationPath "$want"); then
        isError "No such storage location: $want"
        isNotice "Known locations: $(storageLocationNames 2>/dev/null | paste -sd, -)"
        return 1
    fi

    if ! storageRootAvailable "$root"; then
        isError "Storage location '$want' ($root) is not mounted — refusing to install onto it."
        isNotice "Mount it first, or leave the location unset to use the default."
        return 1
    fi

    if [[ -e "${root%/}/$app" ]]; then
        isError "'${root%/}/$app' already exists — refusing to install over it."
        return 1
    fi

    # Two records answering at different times: the exported variable is what
    # _appDirIntended reads in THIS process before any config exists for the
    # app; the index is what answers for a later process whose config lives on
    # a drive that is not mounted.
    export "CFG_${app^^}_STORAGE=$want"
    storageIndexSet "$app" "$root"
    storageCacheReset

    isNotice "Installing $app onto '$want' ($root)."
    return 0
}

# Keep the choice, now that there is a deployed config to keep it in.
storagePlaceAppPost()
{
    local app="$1" want="$2"
    [[ -n "$app" && -n "$want" && "$want" != "default" ]] || return 0

    local dir cfg
    dir=$(appDir "$app") || return 0
    cfg="$dir/$app.config"
    [[ -f "$cfg" ]] || return 0

    updateConfigOption "CFG_${app^^}_STORAGE" "$want" "$cfg" >/dev/null 2>&1 || true
    export "CFG_${app^^}_STORAGE=$want"
    declare -f storageSyncAppComment >/dev/null 2>&1 && storageSyncAppComment "$app"
    return 0
}

# config_variables with the choice set, so the later override pass writes it
# rather than resetting it to the template's "default".
storageChoiceMerge()
{
    local app="$1" want="$2" config_vars="${3:-}"
    local key="CFG_${app^^}_STORAGE"
    [[ -n "$want" ]] || { printf '%s' "$config_vars"; return 0; }

    local -a keep=() pairs=()
    local pair
    IFS='|' read -ra pairs <<< "$config_vars"
    for pair in "${pairs[@]}"; do
        [[ -z "$pair" || "$pair" == "$key="* ]] && continue
        keep+=("$pair")
    done
    keep+=("$key=$want")

    local out="" p
    for p in "${keep[@]}"; do
        [[ -n "$out" ]] && out+="|"
        out+="$p"
    done
    printf '%s' "$out"
}

# Every location an app can be installed onto, one per line.
storageLocationNames()
{
    printf '%s\n' primary
    local root
    while IFS= read -r root; do
        [[ -z "$root" ]] && continue
        [[ "${root%/}" == "$(primaryRoot)" ]] && continue
        storageLocationName "$root"
    done < <(storageRoots 2>/dev/null)
}