<?php

declare(strict_types=1);

// Post-update hook and migration runner.
//
// Runs as the last step of manageUpdateApply(), after the files are in place.
// Two independent mechanisms, either or both:
//
//   1. MANAGE_UPDATE_POST_HOOK  – a project callback (clear a cache, rebuild an
//      index, chmod a new directory)
//   2. MANAGE_MIGRATIONS_DIR    – ordered, once-only migration scripts shipped
//      inside the release package
//
// There is no rollback in this client, so a failure here must be loud rather
// than silent: the run stops at the first failing migration, the remaining ones
// stay pending, and the result is reported through the CLI exit code and the
// GUI banner. `manage-client.php migrate` retries once the cause is fixed.

function manageMigrationsEnabled(): bool
{
    $dir = MANAGE_MIGRATIONS_DIR;

    return is_string($dir) && trim($dir) !== "";
}

function manageMigrationsDir(): string
{
    return rtrim((string) MANAGE_MIGRATIONS_DIR, "/\\") . DIRECTORY_SEPARATOR;
}

function manageMigrationsStateFile(): string
{
    return (string) MANAGE_MIGRATIONS_STATE;
}

function manageMigrationsReadState(): array
{
    $state = manageReadJson(manageMigrationsStateFile());
    $applied = isset($state["applied"]) && is_array($state["applied"])
        ? $state["applied"]
        : [];

    return ["applied" => array_values($applied)];
}

function manageMigrationsAppliedIds(): array
{
    $ids = [];
    foreach (manageMigrationsReadState()["applied"] as $entry) {
        if (is_array($entry) && ($entry["id"] ?? "") !== "") {
            $ids[] = (string) $entry["id"];
        }
    }

    return $ids;
}

function manageMigrationsRecordApplied(string $id, int $durationMs): void
{
    $state = manageMigrationsReadState();
    $state["applied"][] = [
        "id" => $id,
        "applied_at" => date(DATE_ATOM),
        "version" => manageClientVersion(),
        "duration_ms" => $durationMs,
    ];

    manageWriteJson(manageMigrationsStateFile(), $state);
}

/**
 * All migration files in the package, sorted by filename.
 *
 * The filename without .php is the migration id, so renaming an already applied
 * migration makes it run again. That is documented, not accidental.
 */
function manageMigrationsAvailable(): array
{
    if (!manageMigrationsEnabled() || !is_dir(manageMigrationsDir())) {
        return [];
    }

    $migrations = [];
    foreach (glob(manageMigrationsDir() . "*.php") ?: [] as $path) {
        if (!is_file($path) || !is_readable($path)) {
            continue;
        }
        $id = basename($path, ".php");
        if ($id === "" || $id[0] === ".") {
            continue;
        }
        $migrations[] = ["id" => $id, "path" => $path];
    }

    usort($migrations, static function (array $left, array $right): int {
        return strcmp($left["id"], $right["id"]);
    });

    return $migrations;
}

/**
 * Migrations that have not been applied yet, in execution order.
 */
function manageUpdatePendingMigrations(): array
{
    $applied = manageMigrationsAppliedIds();
    $pending = [];

    foreach (manageMigrationsAvailable() as $migration) {
        if (!in_array($migration["id"], $applied, true)) {
            $pending[] = $migration;
        }
    }

    return $pending;
}

// Builds the context handed to every migration and to the post-update hook.
function manageHookContext(array $extra = []): array
{
    $context = array_merge([
        "app_root" => manageClientAppRoot(),
        "instance" => (string) MANAGE_INSTANCE,
        "from_version" => "",
        "to_version" => manageClientVersion(),
        "backup_dir" => "",
        "run_id" => "",
    ], $extra);

    // A database-backed project gets a ready connection, so a migration never
    // has to duplicate the credentials that are already configured for backups.
    if (manageDatabaseConfigured()) {
        $context["pdo"] = manageDatabaseConnect();
    }

    return $context;
}

/**
 * Loads one migration file and returns its callable.
 *
 * Two supported shapes:
 *   return function (array $context): void { ... };
 *   function up(array $context): void { ... }   // defined in the file
 */
function manageMigrationResolveCallable(array $migration): callable
{
    $returned = require $migration["path"];

    if (is_callable($returned)) {
        return $returned;
    }

    if (function_exists("up")) {
        return "up";
    }

    throw new RuntimeException(
        "Migration " . $migration["id"] . " liefert keine Funktion zurück und definiert kein up().",
    );
}

/**
 * Runs all pending migrations in order.
 *
 * Stops at the first failure; later migrations stay pending. Returns a report
 * rather than throwing, so a caller can distinguish "deployment succeeded but
 * a migration failed" from "deployment failed".
 *
 * @return array{success: bool, applied: array, failed: string|null, error: string|null, pending: int}
 */
function manageUpdateRunMigrations(array $context = []): array
{
    $report = [
        "success" => true,
        "applied" => [],
        "failed" => null,
        "error" => null,
        "pending" => 0,
    ];

    $pending = manageUpdatePendingMigrations();
    if ($pending === []) {
        return $report;
    }

    $baseContext = manageHookContext($context);

    foreach ($pending as $position => $migration) {
        $startedAt = microtime(true);

        try {
            // Each migration is loaded in its own function scope. A file that
            // defines up() twice across two migrations would collide, which is
            // why the "return a closure" form is the documented default.
            $callable = manageMigrationResolveCallable($migration);
            $callable(array_merge($baseContext, ["migration_id" => $migration["id"]]));
        } catch (Throwable $exception) {
            $report["success"] = false;
            $report["failed"] = $migration["id"];
            $report["error"] = $exception->getMessage();
            $report["pending"] = count($pending) - $position;

            manageClientLog("ERROR", "Migration failed", [
                "migration" => $migration["id"],
                "error" => $exception->getMessage(),
            ]);

            return $report;
        }

        $durationMs = (int) round((microtime(true) - $startedAt) * 1000);
        manageMigrationsRecordApplied($migration["id"], $durationMs);
        $report["applied"][] = $migration["id"];

        manageClientLog("INFO", "Migration applied", [
            "migration" => $migration["id"],
            "duration_ms" => $durationMs,
        ]);
    }

    return $report;
}

/**
 * Runs the configured project callback.
 *
 * @return array{configured: bool, success: bool, error: string|null}
 */
function manageUpdateRunPostHookCallback(array $context = []): array
{
    $hook = MANAGE_UPDATE_POST_HOOK;
    if (!is_array($hook) || ($hook["callback"] ?? null) === null) {
        return ["configured" => false, "success" => true, "error" => null];
    }

    try {
        $file = trim((string) ($hook["file"] ?? ""));
        if ($file !== "") {
            if (!is_file($file)) {
                throw new RuntimeException("Hook-Datei wurde nicht gefunden: " . $file);
            }
            require_once $file;
        }

        $callback = $hook["callback"];
        if (!is_callable($callback)) {
            throw new RuntimeException(
                "Hook-Callback ist nicht aufrufbar: " . (is_string($callback) ? $callback : gettype($callback)),
            );
        }

        $result = call_user_func($callback, manageHookContext($context));
        if ($result === false || (is_array($result) && ($result["success"] ?? true) === false)) {
            $error = is_array($result) ? trim((string) ($result["error"] ?? "")) : "";
            throw new RuntimeException(
                "Post-Update-Hook meldet einen Fehler" . ($error !== "" ? ": " . $error : "."),
            );
        }
    } catch (Throwable $exception) {
        manageClientLog("ERROR", "Post-update hook failed", [
            "error" => $exception->getMessage(),
        ]);

        return ["configured" => true, "success" => false, "error" => $exception->getMessage()];
    }

    manageClientLog("INFO", "Post-update hook finished", []);

    return ["configured" => true, "success" => true, "error" => null];
}

/**
 * Full post-update step: migrations first, then the project callback.
 *
 * Migrations run first so the callback can rely on the new schema. When a
 * migration fails the callback is skipped, because running it against a
 * half-migrated state is worse than not running it at all.
 *
 * @return array{success: bool, migrations: array, hook: array, error: string|null, failed_migration: string|null}
 */
function manageUpdateRunPostHook(array $context = []): array
{
    $migrations = manageUpdateRunMigrations($context);

    if (!$migrations["success"]) {
        return [
            "success" => false,
            "migrations" => $migrations,
            "hook" => ["configured" => false, "success" => true, "error" => null, "skipped" => true],
            "error" => $migrations["error"],
            "failed_migration" => $migrations["failed"],
        ];
    }

    $hook = manageUpdateRunPostHookCallback(array_merge($context, [
        "migrations" => $migrations["applied"],
    ]));

    return [
        "success" => $hook["success"],
        "migrations" => $migrations,
        "hook" => $hook,
        "error" => $hook["error"],
        "failed_migration" => null,
    ];
}