// dataset_hash.cpp - C API implementation using C-style internals
#include "dataset_hash.h"
#include "crypto/sha256_hasher.h"
#include "io/file_hash.h"
#include "threading/parallel_hash.h"
#include "../common/include/secure_mem.h"
#include <cstring>
#include <stdlib.h>

using fetchml::common::safe_strncpy;

// Context structure - simple C-style
struct fh_context {
    ParallelHasher hasher;
    size_t buffer_size;
    char last_error[256];
};

fh_context_t* fh_init(uint32_t num_threads) {
    auto* ctx = (fh_context_t*)malloc(sizeof(fh_context_t));
    if (!ctx) return nullptr;
    
    ctx->buffer_size = 64 * 1024;
    ctx->last_error[0] = '\0';
    
    if (!parallel_hasher_init(&ctx->hasher, num_threads, ctx->buffer_size)) {
        free(ctx);
        return nullptr;
    }
    
    return ctx;
}

void fh_cleanup(fh_context_t* ctx) {
    if (ctx) {
        parallel_hasher_cleanup(&ctx->hasher);
        free(ctx);
    }
}

char* fh_hash_file(fh_context_t* ctx, const char* path) {
    if (!ctx || !path) return nullptr;
    
    char hash[65];
    if (hash_file(path, ctx->buffer_size, hash) != 0) {
        safe_strncpy(ctx->last_error, "Failed to hash file", sizeof(ctx->last_error));
        return nullptr;
    }
    
    char* result = (char*)malloc(65);
    if (result) {
        memcpy(result, hash, 65);
    }
    return result;
}

char* fh_hash_directory(fh_context_t* ctx, const char* path) {
    if (!ctx || !path) return nullptr;
    
    char* result = (char*)malloc(65);
    if (!result) return nullptr;
    
    if (parallel_hash_directory(&ctx->hasher, path, result) != 0) {
        free(result);
        safe_strncpy(ctx->last_error, "Failed to hash directory", sizeof(ctx->last_error));
        return nullptr;
    }
    
    return result;
}

int fh_hash_batch(fh_context_t* ctx, const char** paths, uint32_t count, char** out_hashes) {
    if (!ctx || !paths || !out_hashes || count == 0) return -1;
    
    return hash_files_batch(paths, count, out_hashes, ctx->buffer_size);
}

int fh_hash_directory_batch(
    fh_context_t* ctx,
    const char* dir_path,
    char** out_hashes,
    char** out_paths,
    uint32_t max_results,
    uint32_t* out_count) {
    
    if (!ctx || !dir_path || !out_hashes) return -1;
    
    return parallel_hash_directory_batch(&ctx->hasher, dir_path, out_hashes, out_paths, 
                                          max_results, out_count);
}

char* fh_hash_directory_combined(fh_context_t* ctx, const char* dir_path) {
    return fh_hash_directory(ctx, dir_path);
}

void fh_free_string(char* str) {
    free(str);
}

const char* fh_last_error(fh_context_t* ctx) {
    if (!ctx || !ctx->last_error[0]) return nullptr;
    return ctx->last_error;
}

void fh_clear_error(fh_context_t* ctx) {
    if (ctx) {
        ctx->last_error[0] = '\0';
    }
}

void fh_set_buffer_size(fh_context_t* ctx, size_t buffer_size) {
    if (ctx) {
        ctx->buffer_size = buffer_size;
    }
}

size_t fh_get_buffer_size(fh_context_t* ctx) {
    return ctx ? ctx->buffer_size : 0;
}

int fh_has_simd_sha256(void) {
    return sha256_has_hardware_accel();
}

const char* fh_get_simd_impl_name(void) {
    return sha256_impl_name();
}

// Constant-time hash comparison
int fh_hashes_equal(const char* hash_a, const char* hash_b) {
    if (!hash_a || !hash_b) return 0;
    // SHA256 hex strings are always 64 characters
    return fetchml::common::secure_memcmp(hash_a, hash_b, 64) == 0 ? 1 : 0;
}