/*
 * NOSTR Core Library - NIP-001: Basic Protocol Flow
 * 
 * Event creation, signing, serialization and core protocol functions
 */

#include "nip001.h"
#include "nostr_crypto.h"
#include "../cjson/cJSON.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

// Declare utility functions
void nostr_bytes_to_hex(const unsigned char* bytes, size_t len, char* hex);
int nostr_hex_to_bytes(const char* hex, unsigned char* bytes, size_t len);

/**
 * Initialize the NOSTR library
 */
int nostr_init(void) {
    if (nostr_crypto_init() != 0) {
        return NOSTR_ERROR_CRYPTO_FAILED;
    }
    return NOSTR_SUCCESS;
}

/**
 * Cleanup the NOSTR library
 */
void nostr_cleanup(void) {
    nostr_crypto_cleanup();
}

/**
 * Convert error code to human-readable string
 */
const char* nostr_strerror(int error_code) {
    switch (error_code) {
        case NOSTR_SUCCESS: return "Success";
        case NOSTR_ERROR_INVALID_INPUT: return "Invalid input";
        case NOSTR_ERROR_CRYPTO_FAILED: return "Cryptographic operation failed";
        case NOSTR_ERROR_MEMORY_FAILED: return "Memory allocation failed";
        case NOSTR_ERROR_IO_FAILED: return "I/O operation failed";
        case NOSTR_ERROR_NETWORK_FAILED: return "Network operation failed";
        case NOSTR_ERROR_NIP04_INVALID_FORMAT: return "NIP-04 invalid format";
        case NOSTR_ERROR_NIP04_DECRYPT_FAILED: return "NIP-04 decryption failed";
        case NOSTR_ERROR_NIP04_BUFFER_TOO_SMALL: return "NIP-04 buffer too small";
        case NOSTR_ERROR_NIP05_INVALID_IDENTIFIER: return "NIP-05: Invalid identifier format";
        case NOSTR_ERROR_NIP05_HTTP_FAILED: return "NIP-05: HTTP request failed";
        case NOSTR_ERROR_NIP05_JSON_PARSE_FAILED: return "NIP-05: JSON parsing failed";
        case NOSTR_ERROR_NIP05_NAME_NOT_FOUND: return "NIP-05: Name not found in .well-known";
        case NOSTR_ERROR_NIP05_PUBKEY_MISMATCH: return "NIP-05: Public key mismatch";
        default: return "Unknown error";
    }
}

/**
 * Create and sign a NOSTR event
 */
cJSON* nostr_create_and_sign_event(int kind, const char* content, cJSON* tags, const unsigned char* private_key, time_t timestamp) {
    if (!private_key) {
        return NULL;
    }
    
    if (!content) {
        content = ""; // Default to empty content
    }
    
    // Convert private key to public key
    unsigned char public_key[32];
    if (nostr_ec_public_key_from_private_key(private_key, public_key) != 0) {
        return NULL;
    }
    
    // Convert public key to hex
    char pubkey_hex[65];
    nostr_bytes_to_hex(public_key, 32, pubkey_hex);
    
    // Create event structure
    cJSON* event = cJSON_CreateObject();
    if (!event) {
        return NULL;
    }
    
    // Use provided timestamp or current time if timestamp is 0
    time_t event_time = (timestamp == 0) ? time(NULL) : timestamp;
    
    cJSON_AddStringToObject(event, "pubkey", pubkey_hex);
    cJSON_AddNumberToObject(event, "created_at", (double)event_time);
    cJSON_AddNumberToObject(event, "kind", kind);
    
    // Add tags (copy provided tags or create empty array)
    if (tags) {
        cJSON_AddItemToObject(event, "tags", cJSON_Duplicate(tags, 1));
    } else {
        cJSON_AddItemToObject(event, "tags", cJSON_CreateArray());
    }
    
    cJSON_AddStringToObject(event, "content", content);
    
    // ============================================================================
    // INLINE SERIALIZATION AND SIGNING LOGIC 
    // ============================================================================
    
    // Get event fields for serialization
    cJSON* pubkey_item = cJSON_GetObjectItem(event, "pubkey");
    cJSON* created_at_item = cJSON_GetObjectItem(event, "created_at");
    cJSON* kind_item = cJSON_GetObjectItem(event, "kind");
    cJSON* tags_item = cJSON_GetObjectItem(event, "tags");
    cJSON* content_item = cJSON_GetObjectItem(event, "content");
    
    if (!pubkey_item || !created_at_item || !kind_item || !tags_item || !content_item) {
        cJSON_Delete(event);
        return NULL;
    }
    
    // Create serialization array: [0, pubkey, created_at, kind, tags, content]
    cJSON* serialize_array = cJSON_CreateArray();
    if (!serialize_array) {
        cJSON_Delete(event);
        return NULL;
    }
    
    cJSON_AddItemToArray(serialize_array, cJSON_CreateNumber(0));
    cJSON_AddItemToArray(serialize_array, cJSON_Duplicate(pubkey_item, 1));
    cJSON_AddItemToArray(serialize_array, cJSON_Duplicate(created_at_item, 1));
    cJSON_AddItemToArray(serialize_array, cJSON_Duplicate(kind_item, 1));
    cJSON_AddItemToArray(serialize_array, cJSON_Duplicate(tags_item, 1));
    cJSON_AddItemToArray(serialize_array, cJSON_Duplicate(content_item, 1));
    
    char* serialize_string = cJSON_PrintUnformatted(serialize_array);
    cJSON_Delete(serialize_array);
    
    if (!serialize_string) {
        cJSON_Delete(event);
        return NULL;
    }
    
    // Hash the serialized event
    unsigned char event_hash[32];
    if (nostr_sha256((const unsigned char*)serialize_string, strlen(serialize_string), event_hash) != 0) {
        free(serialize_string);
        cJSON_Delete(event);
        return NULL;
    }
    
    // Convert hash to hex for event ID
    char event_id[65];
    nostr_bytes_to_hex(event_hash, 32, event_id);
    
    // Sign the hash using ECDSA
    unsigned char signature[64];
    if (nostr_ec_sign(private_key, event_hash, signature) != 0) {
        free(serialize_string);
        cJSON_Delete(event);
        return NULL;
    }
    
    // Convert signature to hex
    char sig_hex[129];
    nostr_bytes_to_hex(signature, 64, sig_hex);
    
    // Add ID and signature to the event
    cJSON_AddStringToObject(event, "id", event_id);
    cJSON_AddStringToObject(event, "sig", sig_hex);
    
    free(serialize_string);
    
    return event;
}