From 2358ba4314dc6d757049bc4871ecf2922614b61b Mon Sep 17 00:00:00 2001 From: Perberos Date: Tue, 8 Nov 2011 13:50:37 -0300 Subject: initial --- src/currency.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 244 insertions(+) create mode 100644 src/currency.c (limited to 'src/currency.c') diff --git a/src/currency.c b/src/currency.c new file mode 100644 index 0000000..1900a58 --- /dev/null +++ b/src/currency.c @@ -0,0 +1,244 @@ +#include + +#include +#include +#include +#include +#include +#include + +#include "currency.h" +#include "mp.h" + +typedef struct { + char *short_name; + MPNumber value; +} currency; + +static currency *currencies = NULL; +static int currency_count = 0; + +static gboolean downloading_rates = FALSE; +static gboolean loaded_rates = FALSE; + +static char* +get_rate_filepath() +{ + return g_build_filename(g_get_user_cache_dir (), + "gcalctool", + "eurofxref-daily.xml", + NULL); +} + +static int +currency_get_index(const char *short_name) +{ + int i; + for (i = 0; i < currency_count; i++) { + if (!strcmp(short_name, currencies[i].short_name)) { + if (mp_is_negative(¤cies[i].value) || + mp_is_zero(¤cies[i].value)) { + return -1; + } else { + return i; + } + } + } + return -1; +} + +/* A file needs to be redownloaded if it doesn't exist, or every 7 days. + * When an error occur, it probably won't hurt to try to download again. + */ +static int +currency_rates_needs_update() +{ + gchar *filename = get_rate_filepath (); + struct stat buf; + if (!g_file_test(filename, G_FILE_TEST_IS_REGULAR)) { + g_free(filename); + return 1; + } + + if (g_stat(filename, &buf) == -1) { + g_free(filename); + return 1; + } + g_free(filename); + + if (difftime(time(NULL), buf.st_mtime) > (60 * 60 * 24 * 7)) { + return 1; + } + + return 0; +} + + +static void +download_cb(GObject *object, GAsyncResult *result, gpointer user_data) +{ + GError *error = NULL; + + if (g_file_copy_finish(G_FILE(object), result, &error)) + g_debug("Rates updated"); + else + g_warning("Couldn't download currency file: %s", error->message); + g_clear_error(&error); + downloading_rates = FALSE; +} + + +static void +currency_download_rates() +{ + gchar *filename, *directory; + GFile *source, *dest; + + downloading_rates = TRUE; + g_debug("Downloading rates..."); + + filename = get_rate_filepath(); + directory = g_path_get_dirname(filename); + g_mkdir_with_parents(directory, 0755); + g_free(directory); + + source = g_file_new_for_uri ("http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml"); + dest = g_file_new_for_path (filename); + g_free(filename); + + g_file_copy_async (source, dest, G_FILE_COPY_OVERWRITE, G_PRIORITY_DEFAULT, NULL, NULL, NULL, download_cb, NULL); + g_object_unref(source); + g_object_unref(dest); +} + + +static void +set_rate (xmlNodePtr node, currency *cur) +{ + xmlAttrPtr attribute; + for (attribute = node->properties; attribute; attribute = attribute->next) { + if (strcmp((char *)attribute->name, "currency") == 0) { + cur->short_name = (char *)xmlNodeGetContent((xmlNodePtr) attribute); + } else if (strcmp ((char *)attribute->name, "rate") == 0) { + char *val = (char *)xmlNodeGetContent ((xmlNodePtr) attribute); + mp_set_from_string(val, 10, &(cur->value)); + xmlFree (val); + } + } +} + +static void +currency_load_rates() +{ + char *filename = get_rate_filepath(); + xmlDocPtr document; + xmlXPathContextPtr xpath_ctx; + xmlXPathObjectPtr xpath_obj; + int i, len; + + g_return_if_fail(g_file_test(filename, G_FILE_TEST_IS_REGULAR)); + + xmlInitParser(); + document = xmlReadFile(filename, NULL, 0); + g_free (filename); + if (document == NULL) { + fprintf(stderr, "Couldn't parse data file\n"); + return; + } + + xpath_ctx = xmlXPathNewContext(document); + if (xpath_ctx == NULL) { + xmlFreeDoc(document); + fprintf(stderr, "Couldn't create XPath context\n"); + return; + } + + xmlXPathRegisterNs(xpath_ctx, + BAD_CAST("xref"), + BAD_CAST("http://www.ecb.int/vocabulary/2002-08-01/eurofxref")); + xpath_obj = xmlXPathEvalExpression(BAD_CAST("//xref:Cube[@currency][@rate]"), + xpath_ctx); + + if (xpath_obj == NULL) { + xmlXPathFreeContext(xpath_ctx); + xmlFreeDoc(document); + fprintf(stderr, "Couldn't create XPath object\n"); + return; + } + + len = (xpath_obj->nodesetval) ? xpath_obj->nodesetval->nodeNr : 0; + currency_count = len + 1; + currencies = g_slice_alloc0(sizeof(currency) * currency_count); + for (i = 0; i < len; i++) { + if (xpath_obj->nodesetval->nodeTab[i]->type == XML_ELEMENT_NODE) { + set_rate(xpath_obj->nodesetval->nodeTab[i], ¤cies[i]); + } + + // Avoid accessing removed elements + if (xpath_obj->nodesetval->nodeTab[i]->type != XML_NAMESPACE_DECL) + xpath_obj->nodesetval->nodeTab[i] = NULL; + } + + currencies[len].short_name = g_strdup("EUR"); + MPNumber foo; + mp_set_from_integer(1, &foo); + currencies[len].value = foo; + + xmlXPathFreeObject(xpath_obj); + xmlXPathFreeContext(xpath_ctx); + xmlFreeDoc(document); + xmlCleanupParser(); + + g_debug("Rates loaded"); + loaded_rates = TRUE; +} + + +gboolean +currency_convert(const MPNumber *from_amount, + const char *source_currency, const char *target_currency, + MPNumber *to_amount) +{ + int from_index, to_index; + + if (downloading_rates) + return FALSE; + + /* Update currency if necessary */ + if (currency_rates_needs_update()) { + currency_download_rates(); + return FALSE; + } + if (!loaded_rates) + currency_load_rates(); + + from_index = currency_get_index(source_currency); + to_index = currency_get_index(target_currency); + if (from_index < 0 || to_index < 0) + return FALSE; + + if (mp_is_zero(¤cies[from_index].value) || + mp_is_zero(¤cies[to_index].value)) { + mp_set_from_integer(0, to_amount); + return FALSE; + } + + mp_divide(from_amount, ¤cies[from_index].value, to_amount); + mp_multiply(to_amount, ¤cies[to_index].value, to_amount); + + return TRUE; +} + +void +currency_free_resources() +{ + int i; + + for (i = 0; i < currency_count; i++) { + if (currencies[i].short_name != NULL) + xmlFree(currencies[i].short_name); + } + g_slice_free1(currency_count * sizeof(currency), currencies); + currencies = NULL; + currency_count = 0; +} -- cgit v1.2.1