//! Low-level kernel dispatchers for CUDA Graph capture.
//! These functions write to pre-allocated output buffers and accept an explicit stream.

use std::ffi::c_void;

// Re-declare the extern functions we need (same as in the individual modules)
unsafe extern "C" {
    fn launch_rmsnorm_bf16(
        x: *const c_void,
        gamma: *const c_void,
        out: *mut c_void,
        rows: i32,
        hidden_size: i32,
        eps: f32,
        stream: *mut c_void,
    );
    fn launch_add_rmsnorm_bf16(
        x: *const c_void,
        residual: *const c_void,
        gamma: *const c_void,
        normed_out: *mut c_void,
        sum_out: *mut c_void,
        rows: i32,
        hidden_size: i32,
        eps: f32,
        stream: *mut c_void,
    );
    fn launch_silu_mul_bf16(
        gate: *const c_void,
        up: *const c_void,
        out: *mut c_void,
        n: i32,
        stream: *mut c_void,
    );
    fn launch_add_bf16(
        a: *const c_void,
        b: *const c_void,
        out: *mut c_void,
        n: i32,
        stream: *mut c_void,
    );
    fn launch_embedding_bf16(
        table: *const c_void,
        token_ids: *const c_void,
        out: *mut c_void,
        num_tokens: i32,
        hidden_size: i32,
        vocab_size: i32,
        stream: *mut c_void,
    );
    fn launch_reshape_heads_bf16(
        inp: *const c_void,
        out: *mut c_void,
        seq_len: i32,
        num_heads: i32,
        head_dim: i32,
        stream: *mut c_void,
    );
    fn launch_merge_heads_bf16(
        inp: *const c_void,
        out: *mut c_void,
        seq_len: i32,
        num_heads: i32,
        head_dim: i32,
        stream: *mut c_void,
    );
    fn launch_transpose_hsd_to_shd_bf16(
        inp: *const c_void,
        out: *mut c_void,
        seq_len: i32,
        num_heads: i32,
        head_dim: i32,
        stream: *mut c_void,
    );
    fn launch_transpose_shd_to_hsd_bf16(
        inp: *const c_void,
        out: *mut c_void,
        seq_len: i32,
        num_heads: i32,
        head_dim: i32,
        stream: *mut c_void,
    );
    fn launch_rope_bf16(
        x: *mut c_void,
        cos_cache: *const c_void,
        sin_cache: *const c_void,
        positions: *const c_void,
        num_tokens: i32,
        num_heads: i32,
        head_dim: i32,
        stream: *mut c_void,
    );
    fn launch_gemv_bf16(
        x: *const c_void,
        w: *const c_void,
        y_bf16: *mut c_void,
        y_fp32_buf: *mut c_void,
        k: i32,
        n: i32,
        stream: *mut c_void,
    );
    fn launch_decode_attention_bf16(
        q: *const c_void,
        k: *const c_void,
        v: *const c_void,
        o: *mut c_void,
        batch: i32,
        num_q_heads: i32,
        num_kv_heads: i32,
        kv_len: i32,
        head_dim: i32,
        scale: f32,
        causal: i32,
        stream: *mut c_void,
    );
}

/// Raw rmsnorm dispatch: writes to pre-allocated `out`.
pub unsafe fn rmsnorm_bf16(
    x: *const c_void,
    gamma: *const c_void,
    out: *mut c_void,
    rows: i32,
    hidden_size: i32,
    eps: f32,
    stream: *mut c_void,
) {
    launch_rmsnorm_bf16(x, gamma, out, rows, hidden_size, eps, stream);
}

/// Raw add_rmsnorm dispatch.
pub unsafe fn add_rmsnorm_bf16(
    x: *const c_void,
    residual: *const c_void,
    gamma: *const c_void,
    normed_out: *mut c_void,
    sum_out: *mut c_void,
    rows: i32,
    hidden_size: i32,
    eps: f32,
    stream: *mut c_void,
) {
    launch_add_rmsnorm_bf16(
        x,
        residual,
        gamma,
        normed_out,
        sum_out,
        rows,
        hidden_size,
        eps,
        stream,
    );
}

/// Raw silu_mul dispatch.
pub unsafe fn silu_mul_bf16(
    gate: *const c_void,
    up: *const c_void,
    out: *mut c_void,
    n: i32,
    stream: *mut c_void,
) {
    launch_silu_mul_bf16(gate, up, out, n, stream);
}

/// Raw add dispatch.
pub unsafe fn add_bf16(
    a: *const c_void,
    b: *const c_void,
    out: *mut c_void,
    n: i32,
    stream: *mut c_void,
) {
    launch_add_bf16(a, b, out, n, stream);
}

/// Raw embedding dispatch.
pub unsafe fn embedding_bf16(
    table: *const c_void,
    token_ids: *const c_void,
    out: *mut c_void,
    num_tokens: i32,
    hidden_size: i32,
    vocab_size: i32,
    stream: *mut c_void,
) {
    launch_embedding_bf16(
        table,
        token_ids,
        out,
        num_tokens,
        hidden_size,
        vocab_size,
        stream,
    );
}

/// Raw reshape_heads dispatch.
pub unsafe fn reshape_heads_bf16(
    inp: *const c_void,
    out: *mut c_void,
    seq_len: i32,
    num_heads: i32,
    head_dim: i32,
    stream: *mut c_void,
) {
    launch_reshape_heads_bf16(inp, out, seq_len, num_heads, head_dim, stream);
}

/// Raw merge_heads dispatch.
pub unsafe fn merge_heads_bf16(
    inp: *const c_void,
    out: *mut c_void,
    seq_len: i32,
    num_heads: i32,
    head_dim: i32,
    stream: *mut c_void,
) {
    launch_merge_heads_bf16(inp, out, seq_len, num_heads, head_dim, stream);
}

/// Raw transpose HSD->SHD dispatch.
pub unsafe fn transpose_hsd_to_shd_bf16(
    inp: *const c_void,
    out: *mut c_void,
    seq_len: i32,
    num_heads: i32,
    head_dim: i32,
    stream: *mut c_void,
) {
    launch_transpose_hsd_to_shd_bf16(inp, out, seq_len, num_heads, head_dim, stream);
}

/// Raw transpose SHD->HSD dispatch.
pub unsafe fn transpose_shd_to_hsd_bf16(
    inp: *const c_void,
    out: *mut c_void,
    seq_len: i32,
    num_heads: i32,
    head_dim: i32,
    stream: *mut c_void,
) {
    launch_transpose_shd_to_hsd_bf16(inp, out, seq_len, num_heads, head_dim, stream);
}

/// Raw RoPE dispatch (in-place).
pub unsafe fn rope_bf16(
    x: *mut c_void,
    cos_cache: *const c_void,
    sin_cache: *const c_void,
    positions: *const c_void,
    num_tokens: i32,
    num_heads: i32,
    head_dim: i32,
    stream: *mut c_void,
) {
    launch_rope_bf16(
        x, cos_cache, sin_cache, positions, num_tokens, num_heads, head_dim, stream,
    );
}

/// Raw GEMV dispatch (BF16, M=1). Caller must provide fp32 accumulator buffer.
pub unsafe fn gemv_bf16(
    x: *const c_void,
    w: *const c_void,
    y_bf16: *mut c_void,
    y_fp32_buf: *mut c_void,
    k: i32,
    n: i32,
    stream: *mut c_void,
) {
    launch_gemv_bf16(x, w, y_bf16, y_fp32_buf, k, n, stream);
}

/// Raw decode attention dispatch.
pub unsafe fn decode_attention_bf16(
    q: *const c_void,
    k: *const c_void,
    v: *const c_void,
    o: *mut c_void,
    batch: i32,
    num_q_heads: i32,
    num_kv_heads: i32,
    kv_len: i32,
    head_dim: i32,
    scale: f32,
    stream: *mut c_void,
) {
    launch_decode_attention_bf16(
        q,
        k,
        v,
        o,
        batch,
        num_q_heads,
        num_kv_heads,
        kv_len,
        head_dim,
        scale,
        1,
        stream,
    );
}

// cuBLAS FFI
pub type CublasHandle = *mut c_void;

unsafe extern "C" {
    fn cublasSetStream_v2(handle: CublasHandle, stream: *mut c_void) -> i32;
}

/// Set cuBLAS stream. Must be called before any cuBLAS operations during graph capture.
pub unsafe fn set_cublas_stream(handle: CublasHandle, stream: *mut c_void) {
    cublasSetStream_v2(handle, stream);
}