/*
 * postgresql — a database server shipping multiple services.
 *
 * MULTI-SERVICE PACKAGES
 * ======================
 * Packages that install more than one long-running process can declare
 * multiple named `service` blocks.  Each has its own exec, type, ports,
 * and lifecycle config.  The system config enables them individually using
 * dot-notation (see config.kap):
 *
 *   services {
 *       postgresql.main          { enable = true }
 *       postgresql.checkpointer   { enable = true }
 *       postgresql.walwriter      { enable = true }
 *   }
 *
 * Omitting the dot selects the service named "main".
 *
 *
 * INIT-CONDITIONAL BUILDS
 * =======================
 * The variable ${enabledinit} exposes the configured init system name
 * (from boot.init in config.kap) during the build phase.  Use shell
 * conditionals — no DSL if/else needed:
 *
 *   build {
 *       case ${enabledinit} in
 *           systemd) ./configure --with-systemd --prefix=${prefix} ;;
 *           openrc)  ./configure --with-openrc  --prefix=${prefix} ;;
 *           s6|dinit) ./configure --prefix=${prefix} ;;
 *       esac
 *       make -j${jobs}
 *   }
 *
 * ${enabledinit} is interpolated to the literal init system name
 * ("systemd", "openrc", "s6", or "dinit") before the shell executes the
 * block.  No DSL context-sensitive parsing required.
 *
 *
 * SERVICE TYPE TRANSLATION (for reference)
 * ========================================
 *   semantic  │ systemd    │ openrc              │ s6       │ dinit
 *   ──────────┼────────────┼─────────────────────┼──────────┼──────────
 *   simple    │ Type=simple│ bg=false            │ longrun   │ process
 *   forking   │ Type=fork  │ bg=true             │ longrun   │ bgprocess
 *   notify    │ Type=notify│ bg=true             │ longrun   │ process
 *   oneshot   │ Type=one   │ bg=false, args=""   │ oneshot   │ scripted
 *   longrun   │ Type=simple│ bg=true             │ longrun   │ process
 */
package "postgresql" {
    const version = "16.3"
    const source  = "https://ftp.postgresql.org/pub/source/v${version}/postgresql-${version}.tar.gz"
    sha256 = "a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2"
    license = "PostgreSQL"

    depends = [
        { name = "readline", version = ">=8" },
        { name = "zlib",     version = ">=1.2" },
        { name = "openssl" },
    ]

    conflicts = []   // mutually exclusive packages (e.g. systemd vs eudev)

    features {
        ssl    = { enabled = true, flag = "--with-ssl=openssl" }
        nls    = { enabled = true, flag = "--enable-nls" }
        systemd = { enabled = false, flag = "--with-systemd" }
    }

    config {
        file "etc/postgresql/data/postgresql.conf" mode = "default" {
            port            = ${cfg.port ? 5432}
            max_connections = ${cfg.max_conn ? 100}
            shared_buffers  = ${cfg.shared_buf ? 128MB}
        }
    }

    env {
        CFLAGS  = "-O2"
        // append security hardening flags
        CFLAGS += "-D_FORTIFY_SOURCE=2"
        LDFLAGS = "-Wl,--as-needed"
    }

    // --- services ---------------------------------------------------------
    // PostgreSQL ships the main server plus several auxiliary processes.
    // Each runs as a separate service under the init system.

    // Default service (name = "main").  Enabled via: postgresql { enable = true }
    service main {
        exec        = "/usr/bin/postgres -D /var/lib/postgresql/data"
        type        = "forking"        // postmaster daemonises itself
        user        = "postgres"
        ports       = [5432]
        description = "PostgreSQL database server"
        after       = "network"
        restart     = "always"
        working_dir = "/var/lib/postgresql"
    }

    // Background writer — handles checkpoint I/O.
    service checkpointer {
        exec        = "/usr/bin/postgres-checkpointer"
        type        = "longrun"
        user        = "postgres"
        description = "PostgreSQL checkpointer process"
        restart     = "always"
    }

    // WAL writer — flushes write-ahead log to disk.
    service walwriter {
        exec    = "/usr/bin/postgres-walwriter"
        type    = "longrun"
        user    = "postgres"
        restart = "always"
    }

    // --- build phases ------------------------------------------------------

    prepare {
        tar xf postgresql-${version}.tar.gz
    }

    // init-conditional build: PostgreSQL optionally links against systemd
    // for socket activation and service notification.  Use ${enabledinit}
    // to decide configure flags without per-init service blocks.
    build {
        case ${enabledinit} in
            systemd) ./configure --with-systemd --with-ssl=openssl --prefix=${prefix} ;;
            *)       ./configure --with-ssl=openssl --prefix=${prefix} ;;
        esac
        make -j${jobs} world
    }

    check {
        make check
    }

    install {
        make DESTDIR=${destdir} install-world
    }

    uninstall {
        make DESTDIR=${destdir} uninstall-world
    }

    assert {
        "data directory must exist" : system.config.data_dir != ""
    }
}