#include <stdio.h>
#include <string.h>
#include <stdbool.h>

typedef struct {
    char name[64];
    char data[128];
    int ver;
} AFSFile;

AFSFile server_files[2];
int num_files = 2;

typedef struct {
    char cached_name[64];
    char cached_data[128];
    int cached_ver;
    bool has_callback;
    bool is_dirty;
} VenusCache;

void init_server(void) {
    strcpy(server_files[0].name, "notes.txt");
    strcpy(server_files[0].data, "Hello AFS world");
    server_files[0].ver = 1;
    strcpy(server_files[1].name, "data.bin");
    strcpy(server_files[1].data, "binary stuff");
    server_files[1].ver = 1;
}

void fetch_file(VenusCache *cache, const char *fname) {
    for (int i = 0; i < num_files; i++) {
        if (strcmp(server_files[i].name, fname) == 0) {
            strcpy(cache->cached_name, fname);
            strcpy(cache->cached_data, server_files[i].data);
            cache->cached_ver = server_files[i].ver;
            cache->has_callback = true;
            cache->is_dirty = false;
            printf("FETCH: whole file %s v%d cached locally\n", fname, cache->cached_ver);
            return;
        }
    }
}

void store_file(VenusCache *cache) {
    if (!cache->is_dirty) return;
    for (int i = 0; i < num_files; i++) {
        if (strcmp(server_files[i].name, cache->cached_name) == 0) {
            strcpy(server_files[i].data, cache->cached_data);
            server_files[i].ver++;
            cache->cached_ver = server_files[i].ver;
            cache->is_dirty = false;
            printf("STORE: file %s updated to v%d on server\n", cache->cached_name, server_files[i].ver);
            printf("CALLBACK: notified other clients of change\n");
            return;
        }
    }
}

void local_write(VenusCache *cache, const char *newdata) {
    strcpy(cache->cached_data, newdata);
    cache->is_dirty = true;
    printf("LOCAL WRITE: modified cache of %s\n", cache->cached_name);
}

int main(void) {
    init_server();
    VenusCache client1 = {0};
    VenusCache client2 = {0};
    printf("AFS Simulation Start\n");
    fetch_file(&client1, "notes.txt");
    local_write(&client1, "Updated notes by client1");
    store_file(&client1);
    fetch_file(&client2, "notes.txt");
    printf("Client2 reads: %s\n", client2.cached_data);
    local_write(&client1, "Second update");
    store_file(&client1);
    printf("After callback, client2 cache invalid, would refetch\n");
    fetch_file(&client2, "notes.txt");
    printf("Client2 now has: %s\n", client2.cached_data);
    printf("AFS Simulation End\n");
    return 0;
}