plugins {
    alias(libs.plugins.androidApplication)
    alias(libs.plugins.composeMultiplatform)
    alias(libs.plugins.composeCompiler)
    alias(libs.plugins.ktfmt)
}

// See the root build script for why this style and not ktfmt's default.
ktfmt { kotlinLangStyle() }

// The CA this app pins is baked in at build time from the certificates on
// the machine doing the build -- `$XDG_CONFIG_HOME/dev-updater/certs/ca.pem`,
// which the server generates on first start. DEV_UPDATER_CA overrides it.
//
// Reading it rather than keeping a pasted copy in the source means the
// trust anchor follows the build machine, the CA's private key never has
// to exist anywhere near this repo, and regenerating a CA needs a rebuild
// instead of a paste -- so a stale constant can't quietly disagree with
// the server the app is trying to reach.
val pinnedCaPath: String =
    System.getenv("DEV_UPDATER_CA")
        ?: "${System.getenv("XDG_CONFIG_HOME") ?: "${System.getProperty("user.home")}/.config"}" +
            "/dev-updater/certs/ca.pem"

abstract class GeneratePinnedCert : DefaultTask() {
    /** Where the certificate is looked for, reported in failures. */
    @get:Input abstract val caPath: Property<String>

    /**
     * The certificate itself, set only when it exists -- so a missing one produces this task's own
     * instructions rather than Gradle's "no such input file", which doesn't say what to run.
     */
    @get:InputFile
    @get:Optional
    @get:PathSensitive(PathSensitivity.NONE)
    abstract val caCertificate: RegularFileProperty

    /** Wired by AGP through `addGeneratedSourceDirectory`. */
    @get:OutputDirectory abstract val outputDir: DirectoryProperty

    @TaskAction
    fun generate() {
        val path = caPath.get()
        val ca = File(path)
        if (!ca.isFile) {
            throw GradleException(
                "No CA certificate at $path.\n" +
                    "Start the server once on this machine first -- it generates the CA the " +
                    "app pins, and the certificate has to exist before an APK can embed it.\n" +
                    "Set DEV_UPDATER_CA=/path/to/ca.pem to build against a different one."
            )
        }
        val pem = ca.readText().trim()
        if (!pem.startsWith("-----BEGIN CERTIFICATE-----")) {
            throw GradleException("$path is not a PEM certificate.")
        }
        // The PEM must start immediately after the opening quotes: a
        // leading newline costs Android's CertificateFactory its
        // "-----BEGIN" sniff, so it tries DER instead and fails at runtime
        // with an ASN.1 decode error, nowhere near this file.
        val file = outputDir.get().file("PinnedCaCertificate.kt").asFile
        file.parentFile.mkdirs()
        file.writeText(
            """
            |// Generated from $path by the generatePinnedCert task. Do not edit.
            |package com.example.devupdater
            |
            |const val PINNED_CA_PEM = ""${'"'}$pem
            |""${'"'}
            |
            """
                .trimMargin()
        )
    }
}

val generatePinnedCert =
    tasks.register<GeneratePinnedCert>("generatePinnedCert") {
        val ca = file(pinnedCaPath)
        caPath.set(pinnedCaPath)
        if (ca.isFile) {
            caCertificate.set(ca)
        }
    }

// AGP 9 wants generated sources registered through the variant API rather
// than added to a source set, so the task dependency is carried properly.
androidComponents {
    onVariants { variant ->
        variant.sources.java?.addGeneratedSourceDirectory(
            generatePinnedCert,
            GeneratePinnedCert::outputDir,
        )
    }
}

android {
    namespace = "com.example.devupdater"
    compileSdk = 37

    defaultConfig {
        applicationId = "com.example.devupdater"
        minSdk = 24
        targetSdk = 37
        versionCode = 1
        versionName = "1.0"
    }
    packaging { resources { excludes += "/META-INF/{AL2.0,LGPL2.1}" } }
    buildTypes { getByName("release") { isMinifyEnabled = false } }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_21
        targetCompatibility = JavaVersion.VERSION_21
    }
}

dependencies {
    implementation(libs.compose.runtime)
    implementation(libs.compose.foundation)
    implementation(libs.compose.material3)
    implementation(libs.compose.ui)
    implementation(libs.androidx.activity.compose)
    // NotificationCompat and ServiceCompat, which are how the
    // version-specific parts of a foreground service get written once
    // rather than behind a check per call. Declared rather than inherited
    // transitively, since this module calls it directly.
    implementation(libs.androidx.core.ktx)
    implementation(libs.zxing.embedded)
    // The half of this app that is the same as ai-app's: pinned TLS, the
    // enrollment store, and the scanner.
    implementation(project(":link"))
}