/*
 * foo — a web server with optional SSL and GUI support.
 *
 * SERVICE MODEL
 * =============
 * Kappa service definitions are init-system-agnostic.  The `service` block
 * describes what the service IS (exec, type, ports, user) — NOT how each init
 * system runs it.  The system config's `boot.init` field (see config.kap)
 * determines which init system's service files get generated at install time:
 *
 *   boot.init = "systemd"  →  generates .service unit files
 *   boot.init = "openrc"   →  generates /etc/init.d scripts
 *   boot.init = "s6"       →  generates s6 service directories
 *   boot.init = "dinit"    →  generates dinit service descriptors
 *   boot.init = "runit"   →  generates runit service directories
 *
 * Per-init blocks (service { systemd { ... } s6 { ... } }) do NOT exist.
 * If a package genuinely needs init-specific behaviour (e.g. different
 * ./configure flags for systemd vs. openrc), use ${enabledinit} in the
 * build phase — see examples/postgres.kap for that pattern.
 *
 * SERVICE TYPE VALUES
 * ===================
 * These are semantic, not init-specific.  Each backend translates them
 * into its own vocabulary:
 *
 *   "simple"   —  foreground process; init manages lifecycle directly.
 *                 systemd: Type=simple    openrc: command_background=false
 *                 s6: type=longrun        dinit: type=process
 *
 *   "forking"  —  process daemonises itself; init tracks the forked PID.
 *                 systemd: Type=forking   openrc: command_background=true
 *                 s6: type=longrun        dinit: type=bgprocess
 *
 *   "notify"   —  foreground process that signals readiness (sd_notify).
 *                 systemd: Type=notify    openrc: command_background=true
 *                 s6: type=longrun        dinit: type=process
 *
 *   "oneshot"  —  runs once and exits (startup tasks, database migrations).
 *                 systemd: Type=oneshot   openrc: command_background=false
 *                 s6: type=oneshot        dinit: type=scripted
 *
 *   "longrun"  —  long-running supervised process (s6/runit idiom).
 *                 systemd: Type=simple    openrc: command_background=true
 *                 s6: type=longrun        dinit: type=process
 *
 * The backend generators handle all translation.  Package authors only
 * need to pick the semantic type that describes their daemon's behaviour.
 */
package "foo" {
    const version = "1.2.3"
    const source  = "https://example.com/foo-${version}.tar.gz"
    sha256 = "e127a709cba24c76de8936cb7083dd768f28cd37eb010492e2f19b71eb1294e4"
    license = "MIT"

    provides  = ["libfoo.so.1", "foo"]
    conflicts = []   // packages this cannot coexist with (e.g. ["eudev"] if this were systemd)

    patches = [
        {
            url    = "https://example.com/fix-build.patch"
            sha256 = "abc123def456"
            level  = 1
        },
        "local-fix.patch"   // local shorthand, no hash
    ]
    outputs  = ["bin", "lib", "dev"]

    depends = [
        { name = "zlib",    version = ">=1.2,<2.0" },
        { name = "openssl", feature = "ssl" },
        { name = "gtk",     feature = "gui", version = ">=3" },
        "gettext:lib"    // name:output shorthand
    ]

    features {
        ssl     = { enabled = true,  flag = "--with-ssl-dir=${cfg.ssl_dir}" }
        gui     = { enabled = false, flag = "--enable-gui" }
        drivers = { enabled = true,  force = true }
        debug   = false
    }

    config {
        // Written once, left alone on rebuild if the user edits it.
        file "etc/foo.conf" mode = "default" {
            hostname    = ${cfg.hostname !}        // required — user must set
            listen_port = ${cfg.port ? 8080}       // optional, default 8080
            ssl_enabled = ${cfg.ssl ? true}        // optional, default true
        }

        // Always overwritten on rebuild.
        file "etc/log.conf" mode = "replace" {
            log_level = ${cfg.log_level ? info}
            log_path  = ${cfg.log_path ? /var/log/foo}
        }

        // Three-way diff on rebuild.
        file "etc/limits.conf" mode = "merge" {
            max_connections = ${cfg.max_conn ? 1024}
        }
    }

    env {
        CFLAGS   = "-O2 -march=native"
        LDFLAGS  = "-Wl,--as-needed"
        CFLAGS  ?= "-g"
    }

    // --- service ----------------------------------------------------------
    // Init-agnostic service definition.  The `type` field is semantic
    // ("forking") — the selected init system's backend translates it into
    // the appropriate native format.  If the package ships multiple
    // services, use named blocks (see examples/postgres.kap).
    service {
        exec        = "/usr/bin/foo"
        type        = "forking"      // daemonises itself
        user        = "foo"
        ports       = [80, 443]
        description = "Foo web server"
        after       = "network"      // ordering hint — systemd After=, OpenRC need, etc.
        restart     = "on-failure"   // "always" | "on-failure" | "never"
    }

    prepare {
        patch "fix-build.patch"
    }

    build {
        ./configure --prefix=${prefix} ${feature.ssl} ${feature.gui}
        make -j${jobs}
    }

    check {
        make check
    }

    install {
        make DESTDIR=${destdir} install
    }

    uninstall {
        make -C build uninstall
    }
}