#include <c_BufferOutputStream.h>

typedef struct {
    c_OutStream_t base;
    char*         data;
    c_size_t      capacity;
    c_size_t      size;
    c_Allocator_t allocator;
} c_BufferOutImpl_t;

static c_err_t _BufferOut_Write(c_OutStream_t* self, const void* buf, c_size_t len, c_size_t* written) {
    c_BufferOutImpl_t* impl = (c_BufferOutImpl_t*)self;
    if (impl->size + len > impl->capacity) {
        c_size_t new_cap = impl->capacity == 0 ? 16 : impl->capacity * 2;
        while (impl->size + len > new_cap) new_cap *= 2;
        char* new_data = (char*)c_Allocator_Realloc(&impl->allocator, impl->data, impl->capacity, new_cap);
        if (!new_data) return C_ERR_NOMEM;
        impl->data = new_data;
        impl->capacity = new_cap;
    }
    memcpy(impl->data + impl->size, buf, len);
    impl->size += len;
    if (written) *written = len;
    return C_SUCCESS;
}

static c_err_t _BufferOut_Flush(c_OutStream_t* self) { (void)self; return C_SUCCESS; }

static void _BufferOut_Destroy(c_OutStream_t* self) {
    c_BufferOutImpl_t* impl = (c_BufferOutImpl_t*)self;
    c_Allocator_t alloc = impl->allocator;
    if (impl->data) c_Allocator_Free(&alloc, impl->data);
    c_Allocator_Free(&alloc, impl);
}

static const c_OutStreamVtbl_t g_BufferOutVtbl = { _BufferOut_Write, _BufferOut_Flush, _BufferOut_Destroy };

c_err_t c_BufferOutputStream_Create(c_OutStream_t** out_stream, c_size_t initial_capacity, c_Allocator_t* allocator) {
    if (!out_stream) return C_ERR_PARAM;
    c_Allocator_t alloc = allocator ? *allocator : c_DefaultAllocator;
    c_BufferOutImpl_t* impl = (c_BufferOutImpl_t*)c_Allocator_Calloc(&alloc, 1, sizeof(c_BufferOutImpl_t));
    if (!impl) return C_ERR_NOMEM;
    impl->base.vtbl = &g_BufferOutVtbl;
    impl->allocator = alloc;
    if (initial_capacity > 0) {
        impl->data = (char*)c_Allocator_Calloc(&impl->allocator, initial_capacity, sizeof(char));
        if (!impl->data) { c_Allocator_Free(&alloc, impl); return C_ERR_NOMEM; }
        impl->capacity = initial_capacity;
    }
    *out_stream = &impl->base;
    return C_SUCCESS;
}

c_err_t c_BufferOutputStream_GetBuffer(c_OutStream_t* self, const void** out_ptr, c_size_t* out_len) {
    if (!self || self->vtbl != &g_BufferOutVtbl || !out_ptr || !out_len) return C_ERR_PARAM;
    c_BufferOutImpl_t* impl = (c_BufferOutImpl_t*)self;
    *out_ptr = impl->data;
    *out_len = impl->size;
    return C_SUCCESS;
}