Matrix operations

import math
from typing import List, Optional

class Matrix:
    def __init__(self, data: List[List[float]]):
        self.data = data
        self.rows = len(data)
        self.cols = len(data[0]) if data else 0

    @classmethod
    def zeros(cls, r: int, c: int) -> "Matrix":
        return cls([[0.0]*c for _ in range(r)])

    def transpose(self) -> "Matrix":
        return Matrix([[self.data[r][c] for r in range(self.rows)]
                       for c in range(self.cols)])

    def matmul(self, B: "Matrix") -> "Matrix":
        C = Matrix.zeros(self.rows, B.cols)
        for i in range(self.rows):
            for j in range(B.cols):
                C.data[i][j] = sum(self.data[i][k]*B.data[k][j]
                                   for k in range(self.cols))
        return C

    def det2(self) -> float:
        assert self.rows == self.cols == 2
        return self.data[0][0]*self.data[1][1] - self.data[0][1]*self.data[1][0]

    def inverse2(self) -> "Matrix":
        d = self.det2()
        assert abs(d) > 1e-10, "المصفوفة منفردة (singular) — لا معكوس لها"
        return Matrix([[ self.data[1][1]/d, -self.data[0][1]/d],
                       [-self.data[1][0]/d,  self.data[0][0]/d]])

    def add_bias(self, bias: List[float]) -> "Matrix":
        """Broadcasting: إضافة متجه تحيز لكل صف"""
        return Matrix([[self.data[i][j] + bias[j]
                        for j in range(self.cols)]
                       for i in range(self.rows)])

    def apply(self, fn) -> "Matrix":
        return Matrix([[fn(x) for x in row] for row in self.data])

    def show(self, label: str = ""):
        shape = f"{self.rows}×{self.cols}"
        if label: print(f"\n{label} ({shape}):")
        for row in self.data:
            cells = "  ".join(f"{x:7.3f}" for x in row)
            print(f"  [ {cells} ]")

# ─── عمليات أساسية ─────────────────────────────────────────
print("📊 عمليات المصفوفات:")
print("=" * 50)

A = Matrix([[1, 2, 3], [4, 5, 6]])
B = Matrix([[7, 8], [9, 10], [11, 12]])
A.show("A (2×3)")
B.show("B (3×2)")

C = A.matmul(B)
C.show("A @ B = C (2×2)")

AT = A.transpose()
AT.show("Aᵀ (3×2)")

# المعكوسة
print(f"\n🔄 المعكوسة (Inverse) وتطبيقها:")
M  = Matrix([[4.0, 7.0], [2.0, 6.0]])
MI = M.inverse2()
I  = M.matmul(MI)
M.show("M")
MI.show("M⁻¹")
I.show("M @ M⁻¹ ≈ Identity")

det_str = f"{M.det2():.2f}"
print(f"  det(M) = {det_str}")

# ─── Forward Pass في Neural Network ───────────────────────
print(f"\n\n🧠 Forward Pass — Neural Network Layer:")
print("-" * 48)

def relu(x: float) -> float: return max(0.0, x)
def sigmoid(x: float) -> float: return 1 / (1 + math.exp(-x))

# Batch: 4 عينات، 3 ميزات
X = Matrix([[0.9, 0.1, 0.8],
            [0.2, 0.7, 0.4],
            [0.5, 0.5, 0.6],
            [0.1, 0.9, 0.2]])
# Layer 1: 3 → 4
W1 = Matrix([[0.2, 0.4, 0.1, 0.3],
             [0.5, 0.1, 0.6, 0.2],
             [0.3, 0.3, 0.2, 0.4]])
b1 = [0.1, 0.1, 0.1, 0.1]
# Layer 2: 4 → 2
W2 = Matrix([[0.3, 0.7],
             [0.5, 0.2],
             [0.4, 0.6],
             [0.1, 0.8]])
b2 = [0.05, 0.05]

X.show("X — Input batch (4×3)")
Z1 = X.matmul(W1).add_bias(b1)
A1 = Z1.apply(relu)
A1.show("A1 = ReLU(X@W1+b1) (4×4)")
Z2 = A1.matmul(W2).add_bias(b2)
A2 = Z2.apply(sigmoid)
A2.show("Output = σ(A1@W2+b2) (4×2)")
print(f"\n✅ هذا هو Forward Pass في Neural Network!")