#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>

typedef enum
{
    Assignment,
    BinaryExpression,
    Boolean,
    Comment,
    Expression,
    ForLoop,
    Identifier,
    Number,
    Return,
    String,
    UnaryExpression
} SyntaxKind;

typedef enum
{
    Negate
} UnaryOperator;

typedef enum
{
    Add,
    Subtract
} BinaryOperator;

typedef union
{
    UnaryOperator unaryOperator;
    BinaryOperator binaryOperator;
} Operator;

typedef union
{
    const char *string;
    uint64_t number;
} Value;

typedef struct Node
{
    SyntaxKind syntaxKind;
    struct Node **children;
    uint32_t childCount;
    union
    {
        UnaryOperator unaryOperator;
        BinaryOperator binaryOperator;
    } operator;
    Value value;
} Node;

const char* SyntaxKindString(SyntaxKind syntaxKind)
{
    switch(syntaxKind)
    {
        case Assignment: return "Assignment";
        case BinaryExpression: return "BinaryExpression";
        case Identifier: return "Identifier";
        case Number: return "Number";
        case String: return "String";
        case UnaryExpression: return "UnaryExpression";
        default: return "Unknown";
    }
}

Node* MakeIdentifierNode(
    const char *id
) {
    Node* node = (Node*) malloc(sizeof(Node));
    node->syntaxKind = Identifier;
    node->value.string = id;
    node->childCount = 0;
    return node;
}

Node* MakeNumberNode(
    const char *numberString
) {
    char *ptr;
    Node* node = (Node*) malloc(sizeof(Node));
    node->syntaxKind = Number;
    node->value.number = strtoul(numberString, &ptr, 10);
    node->childCount = 0;
    return node;
}

Node* MakeStringNode(
    const char *string
) {
    Node* node = (Node*) malloc(sizeof(Node));
    node->syntaxKind = String;
    node->value.string = string;
    node->childCount = 0;
    return node;
}

Node* MakeUnaryNode(
    UnaryOperator operator,
    Node *child
) {
    Node* node = (Node*) malloc(sizeof(Node));
    node->syntaxKind = UnaryExpression;
    node->operator.unaryOperator = operator;
    node->children = malloc(sizeof(Node*));
    node->children[0] = child;
    node->childCount = 1;
    return node;
}

Node* MakeBinaryNode(
    BinaryOperator operator,
    Node *left,
    Node *right
) {
    Node* node = (Node*) malloc(sizeof(Node));
    node->syntaxKind = BinaryExpression;
    node->operator.binaryOperator = operator;
    node->children = malloc(sizeof(Node*) * 2);
    node->children[0] = left;
    node->children[1] = right;
    node->childCount = 2;
    return node;
}

static void PrintBinaryOperator(BinaryOperator expression)
{
    switch (expression)
    {
        case Add:
            printf("+");
            break;

        case Subtract:
            printf("-");
            break;
    }

    printf("\n");
}

static void PrintNode(Node *node)
{
    printf("%s\n", SyntaxKindString(node->syntaxKind));
    switch (node->syntaxKind)
    {
        case BinaryExpression:
            PrintBinaryOperator(node->operator.binaryOperator);
            break;

        case Number:
            printf("%lu\n", node->value.number);
            break;
    }
}

void PrintTree(Node *node)
{
    uint32_t i;
    PrintNode(node);
    for (i = 0; i < node->childCount; i += 1)
    {
        PrintTree(node->children[i]);
    }
}