/*
 * QBE Helper Functions
 *
 * Thin C wrappers called from QBE-generated code for operations
 * that are too complex to inline: float arithmetic, float comparison,
 * string comparison, bitwise ops on floats, and boolean conversion.
 */

#include "quickjs-internal.h"
#include <math.h>

/* Comparison op IDs (must match qbe.cm float_cmp_op_id values) */
enum {
  QBE_CMP_EQ = 0,
  QBE_CMP_NE = 1,
  QBE_CMP_LT = 2,
  QBE_CMP_LE = 3,
  QBE_CMP_GT = 4,
  QBE_CMP_GE = 5
};

/* ============================================================
   Float binary arithmetic
   ============================================================ */

static inline JSValue qbe_float_binop(JSContext *ctx, JSValue a, JSValue b,
                                      double (*op)(double, double)) {
  double da, db;
  JS_ToFloat64(ctx, &da, a);
  JS_ToFloat64(ctx, &db, b);
  double r = op(da, db);
  if (!isfinite(r))
    return JS_NULL;
  return JS_NewFloat64(ctx, r);
}

static double op_add(double a, double b) { return a + b; }
static double op_sub(double a, double b) { return a - b; }
static double op_mul(double a, double b) { return a * b; }

JSValue qbe_float_add(JSContext *ctx, JSValue a, JSValue b) {
  return qbe_float_binop(ctx, a, b, op_add);
}

JSValue qbe_float_sub(JSContext *ctx, JSValue a, JSValue b) {
  return qbe_float_binop(ctx, a, b, op_sub);
}

JSValue qbe_float_mul(JSContext *ctx, JSValue a, JSValue b) {
  return qbe_float_binop(ctx, a, b, op_mul);
}

JSValue qbe_float_div(JSContext *ctx, JSValue a, JSValue b) {
  double da, db;
  JS_ToFloat64(ctx, &da, a);
  JS_ToFloat64(ctx, &db, b);
  if (db == 0.0)
    return JS_NULL;
  double r = da / db;
  if (!isfinite(r))
    return JS_NULL;
  return JS_NewFloat64(ctx, r);
}

JSValue qbe_float_mod(JSContext *ctx, JSValue a, JSValue b) {
  double da, db;
  JS_ToFloat64(ctx, &da, a);
  JS_ToFloat64(ctx, &db, b);
  if (db == 0.0)
    return JS_NULL;
  double r = fmod(da, db);
  if (!isfinite(r))
    return JS_NULL;
  return JS_NewFloat64(ctx, r);
}

JSValue qbe_float_pow(JSContext *ctx, JSValue a, JSValue b) {
  double da, db;
  JS_ToFloat64(ctx, &da, a);
  JS_ToFloat64(ctx, &db, b);
  double r = pow(da, db);
  if (!isfinite(r) && isfinite(da) && isfinite(db))
    return JS_NULL;
  return JS_NewFloat64(ctx, r);
}

/* ============================================================
   Float unary ops
   ============================================================ */

JSValue qbe_float_neg(JSContext *ctx, JSValue v) {
  double d;
  JS_ToFloat64(ctx, &d, v);
  return JS_NewFloat64(ctx, -d);
}

JSValue qbe_float_inc(JSContext *ctx, JSValue v) {
  double d;
  JS_ToFloat64(ctx, &d, v);
  return JS_NewFloat64(ctx, d + 1);
}

JSValue qbe_float_dec(JSContext *ctx, JSValue v) {
  double d;
  JS_ToFloat64(ctx, &d, v);
  return JS_NewFloat64(ctx, d - 1);
}

/* ============================================================
   Float comparison — returns 0 or 1 for QBE branching
   ============================================================ */

int qbe_float_cmp(JSContext *ctx, int op, JSValue a, JSValue b) {
  double da, db;
  JS_ToFloat64(ctx, &da, a);
  JS_ToFloat64(ctx, &db, b);
  switch (op) {
  case QBE_CMP_EQ: return da == db;
  case QBE_CMP_NE: return da != db;
  case QBE_CMP_LT: return da < db;
  case QBE_CMP_LE: return da <= db;
  case QBE_CMP_GT: return da > db;
  case QBE_CMP_GE: return da >= db;
  default: return 0;
  }
}

/* ============================================================
   Boolean conversion wrapper
   ============================================================ */

int qbe_to_bool(JSContext *ctx, JSValue v) {
  return JS_ToBool(ctx, v);
}

/* ============================================================
   Bitwise not on non-int (float -> int32 -> ~)
   ============================================================ */

JSValue qbe_bnot(JSContext *ctx, JSValue v) {
  int32_t i;
  JS_ToInt32(ctx, &i, v);
  return JS_NewInt32(ctx, ~i);
}

/* ============================================================
   Bitwise binary ops on floats (convert both to int32, apply, re-tag)
   ============================================================ */

JSValue qbe_bitwise_and(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, ia & ib);
}

JSValue qbe_bitwise_or(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, ia | ib);
}

JSValue qbe_bitwise_xor(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, ia ^ ib);
}

/* ============================================================
   Shift ops on floats (convert to int32, shift, re-tag)
   ============================================================ */

JSValue qbe_shift_shl(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, ia << (ib & 31));
}

JSValue qbe_shift_sar(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, ia >> (ib & 31));
}

JSValue qbe_shift_shr(JSContext *ctx, JSValue a, JSValue b) {
  int32_t ia, ib;
  JS_ToInt32(ctx, &ia, a);
  JS_ToInt32(ctx, &ib, b);
  return JS_NewInt32(ctx, (uint32_t)ia >> (ib & 31));
}

/* ============================================================
   cell_rt_* — Runtime support for QBE-compiled code
   ============================================================ */

#include <dlfcn.h>
#include <stdio.h>

/* --- Property access --- */

JSValue cell_rt_load_field(JSContext *ctx, JSValue obj, const char *name) {
  return JS_GetPropertyStr(ctx, obj, name);
}

void cell_rt_store_field(JSContext *ctx, JSValue val, JSValue obj,
                         const char *name) {
  JS_SetPropertyStr(ctx, obj, name, val);
}

JSValue cell_rt_load_dynamic(JSContext *ctx, JSValue obj, JSValue key) {
  if (JS_IsInt(key))
    return JS_GetPropertyNumber(ctx, obj, (uint32_t)JS_VALUE_GET_INT(key));
  return JS_GetProperty(ctx, obj, key);
}

void cell_rt_store_dynamic(JSContext *ctx, JSValue val, JSValue obj,
                           JSValue key) {
  if (JS_IsInt(key))
    JS_SetPropertyNumber(ctx, obj, (uint32_t)JS_VALUE_GET_INT(key), val);
  else
    JS_SetProperty(ctx, obj, key, val);
}

JSValue cell_rt_load_index(JSContext *ctx, JSValue arr, JSValue idx) {
  if (JS_IsInt(idx))
    return JS_GetPropertyNumber(ctx, arr, (uint32_t)JS_VALUE_GET_INT(idx));
  return JS_GetProperty(ctx, arr, idx);
}

void cell_rt_store_index(JSContext *ctx, JSValue val, JSValue arr,
                         JSValue idx) {
  if (JS_IsInt(idx))
    JS_SetPropertyNumber(ctx, arr, (uint32_t)JS_VALUE_GET_INT(idx), val);
  else
    JS_SetProperty(ctx, arr, idx, val);
}

/* --- Intrinsic/global lookup --- */

JSValue cell_rt_get_intrinsic(JSContext *ctx, const char *name) {
  return JS_GetPropertyStr(ctx, ctx->global_obj, name);
}

/* --- Closure access ---
   Slot 511 in each frame stores a pointer to the enclosing frame.
   Walking depth levels up the chain gives the target frame. */

#define QBE_FRAME_OUTER_SLOT 511

JSValue cell_rt_get_closure(JSContext *ctx, void *fp, int64_t depth,
                            int64_t slot) {
  JSValue *frame = (JSValue *)fp;
  for (int64_t d = 0; d < depth; d++) {
    void *outer = (void *)(uintptr_t)frame[QBE_FRAME_OUTER_SLOT];
    if (!outer) return JS_NULL;
    frame = (JSValue *)outer;
  }
  return frame[slot];
}

void cell_rt_put_closure(JSContext *ctx, void *fp, JSValue val, int64_t depth,
                         int64_t slot) {
  JSValue *frame = (JSValue *)fp;
  for (int64_t d = 0; d < depth; d++) {
    void *outer = (void *)(uintptr_t)frame[QBE_FRAME_OUTER_SLOT];
    if (!outer) return;
    frame = (JSValue *)outer;
  }
  frame[slot] = val;
}

/* --- Function creation and calling --- */

typedef JSValue (*cell_compiled_fn)(JSContext *ctx, void *fp);

/* Per-module function registry.
   Each native .cm module gets its own dylib. When a module creates closures
   via cell_rt_make_function, we record the dylib handle so the trampoline
   can look up the correct cell_fn_N in the right dylib. */
#define MAX_NATIVE_FN 4096

static struct {
  void *dl_handle;
  int fn_idx;
  void *outer_fp;
} g_native_fn_registry[MAX_NATIVE_FN];

static int g_native_fn_count = 0;

/* Set before executing a native module's cell_main */
static void *g_current_dl_handle = NULL;

static JSValue cell_fn_trampoline(JSContext *ctx, JSValue this_val,
                                  int argc, JSValue *argv, int magic) {
  if (magic < 0 || magic >= g_native_fn_count)
    return JS_ThrowTypeError(ctx, "invalid native function id %d", magic);

  void *handle = g_native_fn_registry[magic].dl_handle;
  int fn_idx = g_native_fn_registry[magic].fn_idx;

  char name[64];
  snprintf(name, sizeof(name), "cell_fn_%d", fn_idx);

  cell_compiled_fn fn = (cell_compiled_fn)dlsym(handle, name);
  if (!fn)
    return JS_ThrowTypeError(ctx, "native function %s not found in dylib", name);

  /* Allocate frame: slot 0 = this, slots 1..argc = args */
  JSValue frame[512];
  memset(frame, 0, sizeof(frame));
  frame[0] = this_val;
  for (int i = 0; i < argc && i < 510; i++)
    frame[1 + i] = argv[i];

  /* Link to outer frame for closure access */
  frame[QBE_FRAME_OUTER_SLOT] = (JSValue)(uintptr_t)g_native_fn_registry[magic].outer_fp;

  return fn(ctx, frame);
}

JSValue cell_rt_make_function(JSContext *ctx, int64_t fn_idx, void *outer_fp) {
  if (g_native_fn_count >= MAX_NATIVE_FN)
    return JS_ThrowTypeError(ctx, "too many native functions (max %d)", MAX_NATIVE_FN);

  int global_id = g_native_fn_count++;
  g_native_fn_registry[global_id].dl_handle = g_current_dl_handle;
  g_native_fn_registry[global_id].fn_idx = (int)fn_idx;
  g_native_fn_registry[global_id].outer_fp = outer_fp;

  return JS_NewCFunction2(ctx, (JSCFunction *)cell_fn_trampoline, "native_fn",
                          255, JS_CFUNC_generic_magic, global_id);
}

/* --- Frame-based function calling --- */

JSValue cell_rt_frame(JSContext *ctx, JSValue fn, int64_t nargs) {
  if (!JS_IsFunction(fn)) {
    JS_ThrowTypeError(ctx, "not a function");
    return JS_EXCEPTION;
  }
  int nr_slots = (int)nargs + 2;
  JSFrameRegister *new_frame = alloc_frame_register(ctx, nr_slots);
  if (!new_frame) return JS_EXCEPTION;
  new_frame->function = fn;
  return JS_MKPTR(new_frame);
}

void cell_rt_setarg(JSValue frame_val, int64_t idx, JSValue val) {
  JSFrameRegister *fr = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_val);
  fr->slots[idx] = val;
}

JSValue cell_rt_invoke(JSContext *ctx, JSValue frame_val) {
  JSFrameRegister *fr = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_val);
  int nr_slots = (int)objhdr_cap56(fr->header);
  int c_argc = (nr_slots >= 2) ? nr_slots - 2 : 0;

  /* Copy args to C stack */
  JSValue args[c_argc > 0 ? c_argc : 1];
  for (int i = 0; i < c_argc; i++)
    args[i] = fr->slots[i + 1];

  JSValue result = JS_Call(ctx, fr->function, fr->slots[0], c_argc, args);
  if (JS_IsException(result))
    return JS_EXCEPTION;
  return result;
}

JSValue cell_rt_goframe(JSContext *ctx, JSValue fn, int64_t nargs) {
  return cell_rt_frame(ctx, fn, nargs);
}

JSValue cell_rt_goinvoke(JSContext *ctx, JSValue frame_val) {
  return cell_rt_invoke(ctx, frame_val);
}

/* --- Array push/pop --- */

void cell_rt_push(JSContext *ctx, JSValue arr, JSValue val) {
  JS_ArrayPush(ctx, &arr, val);
}

JSValue cell_rt_pop(JSContext *ctx, JSValue arr) {
  return JS_ArrayPop(ctx, arr);
}

/* --- Delete --- */

JSValue cell_rt_delete(JSContext *ctx, JSValue obj, JSValue key) {
  int ret = JS_DeleteProperty(ctx, obj, key);
  return JS_NewBool(ctx, ret >= 0);
}

/* --- Typeof --- */

JSValue cell_rt_typeof(JSContext *ctx, JSValue val) {
  if (JS_IsNull(val)) return JS_NewString(ctx, "null");
  if (JS_IsInt(val) || JS_IsNumber(val)) return JS_NewString(ctx, "number");
  if (JS_IsBool(val)) return JS_NewString(ctx, "logical");
  if (JS_IsText(val)) return JS_NewString(ctx, "text");
  if (JS_IsFunction(val)) return JS_NewString(ctx, "function");
  if (JS_IsArray(val)) return JS_NewString(ctx, "array");
  if (JS_IsRecord(val)) return JS_NewString(ctx, "object");
  return JS_NewString(ctx, "unknown");
}

/* --- Text comparison stubs (called from QBE type-dispatch branches) --- */

JSValue cell_rt_lt_text(JSContext *ctx, JSValue a, JSValue b) {
  const char *sa = JS_ToCString(ctx, a);
  const char *sb = JS_ToCString(ctx, b);
  int r = (sa && sb) ? strcmp(sa, sb) < 0 : 0;
  return JS_NewBool(ctx, r);
}

JSValue cell_rt_gt_text(JSContext *ctx, JSValue a, JSValue b) {
  const char *sa = JS_ToCString(ctx, a);
  const char *sb = JS_ToCString(ctx, b);
  int r = (sa && sb) ? strcmp(sa, sb) > 0 : 0;
  return JS_NewBool(ctx, r);
}

JSValue cell_rt_le_text(JSContext *ctx, JSValue a, JSValue b) {
  const char *sa = JS_ToCString(ctx, a);
  const char *sb = JS_ToCString(ctx, b);
  int r = (sa && sb) ? strcmp(sa, sb) <= 0 : 0;
  return JS_NewBool(ctx, r);
}

JSValue cell_rt_ge_text(JSContext *ctx, JSValue a, JSValue b) {
  const char *sa = JS_ToCString(ctx, a);
  const char *sb = JS_ToCString(ctx, b);
  int r = (sa && sb) ? strcmp(sa, sb) >= 0 : 0;
  return JS_NewBool(ctx, r);
}

JSValue cell_rt_eq_tol(JSContext *ctx, JSValue a, JSValue b) {
  return JS_NewBool(ctx, a == b);
}

JSValue cell_rt_ne_tol(JSContext *ctx, JSValue a, JSValue b) {
  return JS_NewBool(ctx, a != b);
}

/* --- Disruption --- */

void cell_rt_disrupt(JSContext *ctx) {
  JS_ThrowTypeError(ctx, "type error in native code");
}

/* --- Module entry point ---
   Loads a native .cm module from a dylib handle.
   Looks up cell_main, builds a heap-allocated frame, sets
   g_current_dl_handle so closures register in the right module. */

JSValue cell_rt_native_module_load(JSContext *ctx, void *dl_handle) {
  cell_compiled_fn fn = (cell_compiled_fn)dlsym(dl_handle, "cell_main");
  if (!fn)
    return JS_ThrowTypeError(ctx, "cell_main not found in native module dylib");

  /* Set current handle so cell_rt_make_function registers closures
     against this module's dylib */
  void *prev_handle = g_current_dl_handle;
  g_current_dl_handle = dl_handle;

  /* Heap-allocate so closures created in cell_main can reference
     this frame after the module entry returns. */
  JSValue *frame = calloc(512, sizeof(JSValue));
  if (!frame) {
    g_current_dl_handle = prev_handle;
    return JS_ThrowTypeError(ctx, "frame allocation failed");
  }

  JSValue result = fn(ctx, frame);
  g_current_dl_handle = prev_handle;
  return result;
}

/* Load a native module from a dylib handle, trying a named symbol first.
   Falls back to cell_main if the named symbol is not found. */
JSValue cell_rt_native_module_load_named(JSContext *ctx, void *dl_handle, const char *sym_name) {
  cell_compiled_fn fn = NULL;
  if (sym_name)
    fn = (cell_compiled_fn)dlsym(dl_handle, sym_name);
  if (!fn)
    fn = (cell_compiled_fn)dlsym(dl_handle, "cell_main");
  if (!fn)
    return JS_ThrowTypeError(ctx, "symbol not found in native module dylib");

  void *prev_handle = g_current_dl_handle;
  g_current_dl_handle = dl_handle;

  JSValue *frame = calloc(512, sizeof(JSValue));
  if (!frame) {
    g_current_dl_handle = prev_handle;
    return JS_ThrowTypeError(ctx, "frame allocation failed");
  }

  JSValue result = fn(ctx, frame);
  g_current_dl_handle = prev_handle;
  return result;
}

/* Backward-compat: uses RTLD_DEFAULT (works when dylib opened with RTLD_GLOBAL) */
JSValue cell_rt_module_entry(JSContext *ctx) {
  void *handle = dlopen(NULL, RTLD_LAZY);
  return cell_rt_native_module_load(ctx, handle);
}