#!/bin/bash

# Make sure the state directory exists and create it if not
ensure_state_dir() {
    local state_dir="${STATE_DIR:?}"

    if ! [ -d "$(dirname "$state_dir")" ]; then
        errlog "ERROR: Parent directory of STATE_DIR '$state_dir' doesn't exist."
        return 1
    elif ! [ -d "$state_dir" ]; then
        if ! mkdir "$state_dir"; then
            errlog "ERROR: Failed to create STATE_DIR '$state_dir'."
            return 2
        fi
    fi
}

# Get the configured TTL for a state key
get_state_ttl() {
    local state_file="${1:?Missing state file}"
    local ttl_file="$state_file.ttl"
    local state_ttl

    state_ttl="$(cat "$ttl_file" 2>/dev/null)"

    if ! is_int "$state_ttl"; then
        errlog "WARN: Invalid value '$state_ttl' in '$ttl_file'. Assuming value 0."
        state_ttl=0
    fi

    echo "$state_ttl"
}

# Get the age of a state key
get_state_age() {
    local state_file="${1:?Missing state file}"
    local state_mod

    state_mod="$(stat -c%Y "$state_file")"
    echo "$(($(current_ue) - state_mod))"
}

# Check if a state has expired
state_is_expired() {
    local state_file="${1:?Missing state file}"
    local state_ttl state_mod

    state_ttl="$(get_state_ttl "$state_file")"
    [ "$state_ttl" -eq 0 ] && return 1
    [ "$(get_state_age "$state_file")" -gt "$state_ttl" ] && return 0
}

# Remove a state
rm_state() {
    local key="${1:?Missing key}"
    local state_file="$STATE_DIR/$key"
    local ttl_file="$state_file.ttl"
    rm "$state_file" "$ttl_file"
}

# Check if a state key name is valid
state_key_is_valid() {
    local key="${1:?Missing key}" regex="^([0-9]|[a-z]|[A-Z]|-)*$"

    if ! [[ "$key" =~ $regex ]]; then
        errlog "ERROR: Key '$key' doesn't match regex '$regex'."
        return 1
    fi
}

# Write a value to a state key and optionally set a TTL
set_state() {
    local key="${1:?Missing key}" value="$2" ttl="${3:-0}"
    local state_file="$STATE_DIR/$key"
    local ttl_file="$state_file.ttl"

    state_key_is_valid "$key" || return 1
    ensure_state_dir || return 2

    echo "$value" >"$state_file"
    echo "$ttl" >"$ttl_file"
}

# Read a value from a state key
get_state() {
    local key="${1:?Missing key}"
    local state_file="$STATE_DIR/$key"

    state_key_is_valid "$key" || return 1
    ensure_state_dir || return 2

    if ! [ -f "$state_file" ]; then
        errlog "WARN: State file doesn't exist: '$state_file'"
        return 3
    elif state_is_expired "$state_file"; then
        errlog "WARN: State file has expired: '$state_file'"
        rm_state "$key"
        return 4
    fi

    cat "$state_file"
}