// Session 78 — tiny health HTTP server for containers / ops probes.
// Needs full POSIX runtime (sockets). Not TLS — use Nexus for HTTPS.
import Std::Io::{Print, PrintLine, PrintInt};
import Std::Net::{Net_Create, Net_SetReuse, Net_Bind, Net_Listen, Net_Accept, Net_Send, Net_Recv, Net_Close};
import Std::String::{String_Len, String_Contains, String_FromInt, String_Concat, String_ToInt};
import Std::Os::{Os_GetEnv, Os_InstallStopHandlers, Os_ShouldStop, Os_SetStopListenFd};

func HealthBody() -> String {
    return "{\"status\":\"ok\",\"server\":\"bux-health\",\"version\":\"0.1.0\"}\n";
}

func BuildHttp(body: String) -> String {
    let n: int = String_Len(body) as int;
    return String_Concat(
    String_Concat(
    "HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: ",
    String_FromInt(n as int64)
    ),
    String_Concat("\r\nConnection: close\r\n\r\n", body)
    );
}

func Main() -> int {
    var port: int = 8080;
    let pe: String = Os_GetEnv("HEALTH_PORT");
    if String_Len(pe) > 0 {
        let p: int64 = String_ToInt(pe);
        if p > 0 && p < 65536 {
            port = p as int;
        }
    }
    var bind: String = "0.0.0.0";
    let bindEnv: String = Os_GetEnv("HEALTH_BIND");
    if String_Len(bindEnv) > 0 {
        bind = bindEnv;
    }

    Os_InstallStopHandlers();
    let fd: int = Net_Create();
    if fd < 0 {
        PrintLine("socket failed");
        return 1;
    }
    discard Net_SetReuse(fd);
    if !Net_Bind(fd, bind, port) {
        PrintLine("bind failed");
        return 1;
    }
    if !Net_Listen(fd, 64) {
        PrintLine("listen failed");
        return 1;
    }
    Os_SetStopListenFd(fd);
    Print("health listening on http://");
    Print(bind);
    Print(":");
    PrintInt(port);
    PrintLine("");

    let body: String = HealthBody();
    let resp: String = BuildHttp(body);

    while !Os_ShouldStop() {
        let c: int = Net_Accept(fd);
        if c < 0 {
            if Os_ShouldStop() { break; }
            continue;
        }
        let raw: String = Net_Recv(c, 4096);
        if String_Contains(raw, "GET ") {
            discard Net_Send(c, resp);
        }
        Net_Close(c);
    }
    Net_Close(fd);
    PrintLine("health: stopped");
    return 0;
}