// Current-directory PEB cache smoke test.
// Verifies that SysSetCwd updates the user-visible PEB cache without a getter syscall.

#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <ntlite/syscall.h>

// Prints one NUL-terminated string to the kernel console.
static void print(const char* s) {
    SYS_WRITE_CONSOLE_REQUEST req = { SysSvFromCstr(s) };
    SysWriteConsole(&req);
}

// Prints one unsigned integer to the kernel console.
static void print_u64(uint64_t v) {
    char buf[32];
    int i = 0;
    if (v == 0) {
        print("0");
        return;
    }
    while (v && i < (int)sizeof(buf)) {
        buf[i++] = (char)('0' + (v % 10));
        v /= 10;
    }
    while (i--) {
        char c = buf[i];
        SYS_WRITE_CONSOLE_REQUEST req = { SysSvFromParts(&c, 1) };
        SysWriteConsole(&req);
    }
}

// Terminates the current test process.
static void exit_now(int code) {
    while (true) SysExitProcess(code);
}

// Fails the test with one status value.
static void fail_status(const char* what, uint32_t status) {
    print("cwd_peb_smoke: ");
    print(what);
    print(" status=");
    print_u64(status);
    print("\n");
    exit_now(1);
}

// Fails the test with a simple message.
static void fail(const char* what) {
    print("cwd_peb_smoke: ");
    print(what);
    print("\n");
    exit_now(1);
}

// Copies a string view into a NUL-terminated buffer.
static int copy_view(char* dst, size_t cap, SYS_STRING_VIEW view) {
    if (!dst || cap == 0 || !view.Data || view.Length + 1 > cap)
        return 0;
    memcpy(dst, view.Data, view.Length);
    dst[view.Length] = '\0';
    return 1;
}

// Computes the parent of one canonical native current-directory string.
static int parent_of_cwd(const char* cwd, char* out, size_t cap) {
    if (!cwd || !out || cap == 0)
        return 0;

    size_t len = strlen(cwd);
    if (len < 3 || cwd[1] != ':' || (cwd[2] != '/' && cwd[2] != '\\'))
        return 0;
    if (len + 1 > cap)
        return 0;

    memcpy(out, cwd, len + 1);
    while (len > 3 && (out[len - 1] == '/' || out[len - 1] == '\\'))
        out[--len] = '\0';
    if (len <= 3) {
        out[0] = cwd[0];
        out[1] = ':';
        out[2] = '/';
        out[3] = '\0';
        return 1;
    }

    size_t pos = len;
    while (pos > 3 && out[pos - 1] != '/' && out[pos - 1] != '\\')
        pos--;
    if (pos <= 3) {
        out[0] = cwd[0];
        out[1] = ':';
        out[2] = '/';
        out[3] = '\0';
    } else {
        out[pos - 1] = '\0';
    }
    return 1;
}

// Sets the current directory to one native path.
static void set_cwd_or_fail(const char* path, const char* what) {
    SYS_PATH_REQUEST req = { SysSvFromCstr(path) };
    uint32_t status = SysSetCwd(&req);
    if (status != NTLSTATUS_SUCCESS) fail_status(what, status);
}

// Verifies the current-directory PEB view against one native path.
static void expect_cwd(const char* expected) {
    SYS_STRING_VIEW cwd = SysGetCurrentDirectoryView();
    size_t expectedLen = strlen(expected);
    if (cwd.Length != expectedLen) fail("cwd length mismatch");
    if (cwd.Length && !cwd.Data) fail("cwd data missing");
    if (cwd.Length && memcmp(cwd.Data, expected, cwd.Length) != 0) fail("cwd value mismatch");
}

// Program entry point.
int main(void) {
    char original[SYS_CWD_MAX];
    char parent[SYS_CWD_MAX];

    print("cwd_peb_smoke: start\n");

    SYS_PEB* peb = SysGetPeb();
    if (!peb) fail("peb missing");
    if (peb->Magic != SYS_PEB_MAGIC) fail("peb magic mismatch");
    if (peb->Version != SYS_ENV_VERSION) fail("peb version mismatch");

    if (!copy_view(original, sizeof(original), SysGetCurrentDirectoryView()))
        fail("initial cwd missing");
    if (!parent_of_cwd(original, parent, sizeof(parent)))
        fail("initial cwd malformed");

    set_cwd_or_fail(".", "set dot cwd");
    expect_cwd(original);

    set_cwd_or_fail("..", "set parent cwd");
    expect_cwd(parent);

    set_cwd_or_fail(original, "restore original cwd");
    expect_cwd(original);

    print("cwd_peb_smoke: PASS\n");
    exit_now(0);
    return 0;
}