/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

import java.text.SimpleDateFormat

/**
 * Generates a "unique" versionCode for release builds.
 *
 * The resulting versionCode depends on the local timezone of the machine running this script.
 * This is OK because we only use this for release builds on CI, where the timezone is fixed.
 *
 * Format: byDDDHHmm
 *   - b    = base / epoch digit
 *            Historically hardcoded to "3". This digit is incremented when the year-derived
 *            component overflows its single digit (e.g., in 2026).
 *   - y    = 1 digit derived from (two-digit year - 16), modulo 10
 *   - DDD  = day of year (001–366), zero-padded to 3 digits
 *   - HHmm = 24h time (00–23)(00–59)
 *
 * Example:
 *   Sept 6, 2017 @ 09:41
 *     year = 17 - 16 = 1
 *     base = 3
 *     -> 3-1-249-09-41 -> 312490941
 *
 * Historical note:
 *   Focus first shipped in 2017. The original scheme unconditionally used (yy - 16) which
 *   only fit in a single digit from 2017–2025.
 *
 * 2026 rollover:
 *   In 2026, (yy - 16) became 10. Allowing this to grow to two digits breaks the intended
 *   byDDDHHmm layout and can exceed Play / int limits.
 *
 *   To preserve:
 *     - a single-digit `y`
 *     - monotonic versionCodes across year boundaries
 *
 *   we keep `y` as (yearOffset % 10) and carry overflow into the base digit:
 *     2025 -> base=3, y=9 -> 39DDDHHmm
 *     2026 -> base=4, y=0 -> 40DDDHHmm
 */
ext {
    // "Epoch" digit(s). Historically this was "3".
    // We bump it by +1 each time (yy - 16) crosses another multiple of 10 (i.e., 2026, 2036, ...).
    def epochDigit = 3

    def today = new Date()

    def yy = (new SimpleDateFormat("yy").format(today) as int)
    def yearOffset = yy - 16 // 2017 -> 1, 2025 -> 9, 2026 -> 10, etc.
    if (yearOffset < 0) {
        throw new GradleException(
            "versionCode yearOffset underflow: yearOffset=$yearOffset (yy=$yy)."
        )
    }

    // Keep the "y" component as one digit, and carry overflow into the epoch digit.
    def carry = (int) (yearOffset / 10)
    def yearDigit = (int) (yearOffset % 10)

    def epoch = epochDigit + carry
    if (epoch >= 10) {
        throw new GradleException(
            "versionCode epoch overflow: epoch=$epoch (yy=$yy). Update versionCode scheme."
        )
    }

    // We use the day in the Year (e.g. 248) as opposed to month + day (0510) because it's one digit shorter.
    // If needed we pad with zeros (e.g. 25 -> 025)
    def day = String.format("%03d", (new SimpleDateFormat("D").format(today) as int))

    // We append the hour in day (24h) and minute in hour (7:26 pm -> 1926). We do not append
    // seconds. This assumes that we do not need to build multiple release(!) builds the same
    // minute.
    def time = new SimpleDateFormat("HHmm").format(today)

    // Build the final versionCode using the previously-calculated inputs.
    def versionCode = ("${epoch}${yearDigit}${day}${time}" as long)

    // The Play Console has historically enforced a 2,100,000,000 cap. Keep a defensive ceiling here.
    // Even without this, Android requires versionCode to fit in a signed 32-bit int.
    def MAX_VERSION_CODE = 2_100_000_000
    if (versionCode > MAX_VERSION_CODE) {
        throw new GradleException(
            "Generated versionCode exceeds MAX_VERSION_CODE ($MAX_VERSION_CODE): $versionCode (from $versionCodeStr)"
        )
    }
    if (versionCode > Integer.MAX_VALUE) {
        throw new GradleException(
            "Generated versionCode exceeds Integer.MAX_VALUE: $versionCode (from $versionCodeStr)"
        )
    }

    generatedVersionCode = (versionCode as int)
    println("Generated versionCode: $generatedVersionCode")
    println()
}