#include <stdio.h>
#include <stdlib.h>
#include "lex.h"
#include "parser.h"
#include "ps_graph.h"
#include "error_buffer.h"

static void print_usage(FILE *f, const char *name) {
    fprintf(f, "Usage: %s <function> <output file> [<range>]\n", name);
    fprintf(f, " <function> ..... The function to plot the graph of.\n");
    fprintf(f, " <output file> .. Name of the output PostScript file.\n");
    fprintf(f, " <range> ........ Ranges of the graph in the format of \"xMin:xMax:yMin:yMax\". Optional.\n");

}

static int read_double(const char **str, double *out) {
    char *end;
    *out = strtod(*str, &end);

    if (*str == end)
        return 0;

    *str = end;
    return 1;
}

#define EXPECT_DOUBLE(str, out) \
    if (!read_double(&str, out)) \
        return 0;

#define EXPECT_CHAR(str, c) \
    if (*str++ != c) \
        return 0;

static int parse_range(const char *str, struct graph_range *range) {
    EXPECT_DOUBLE(str, &range->xmin);
    EXPECT_CHAR(str, ':');
    EXPECT_DOUBLE(str, &range->xmax);
    EXPECT_CHAR(str, ':');
    EXPECT_DOUBLE(str, &range->ymin);
    EXPECT_CHAR(str, ':');
    EXPECT_DOUBLE(str, &range->ymax);
    EXPECT_CHAR(str, '\0');
    return 1;
}

static enum error_code export_to_file(const struct expr_node *node, const struct graph_range *range, const char *function, const char *out_name) {
    FILE *file;

    if (!(file = fopen(out_name, "w"))) {
        fprintf(stderr, "Cannot open \"%s\" for writing!\n", out_name);
        return ERR_INVALID_FILENAME;
    }
    
    ps_generate_graph(file, node, range, function);

    fclose(file);
    return ERR_NO_ERR;
}

#ifdef ENABLE_GRAPHVIZ_EXPORT
static void export_gv(const struct expr_node *node, const char *out_name) {
    FILE *file;

    if (!(file = fopen(out_name, "w"))) {
        fprintf(stderr, "GV: Cannot open \"%s\" for writing!\n", out_name);
        return;
    }

    node_debug_print_gv(node, file);

    fclose(file);
}
#endif /* ENABLE_GRAPHVIZ_EXPORT */

int main(int argc, char *argv[]) { 
    enum error_code err;
    struct parser parser;
    struct expr_node *node;
    struct graph_range range;

    if (argc < 3) {
        print_usage(stderr, argv[0]);
        return ERR_INVALID_ARGS;
    }

    if (argc > 3) {
        if (!parse_range(argv[3], &range)) {
            fprintf(stderr, "Invalid format of ranges! The correct format is \"xMin:xMax:yMin:yMax\".\n");
            return ERR_INVALID_LIMITS;
        }
    }
    else {
        range.xmin = -10.0;
        range.xmax = 10.0;
        range.ymin = -10.0;
        range.ymax = 10.0;
    }

    node = parser_parse(&parser, argv[1], "x");

    if (!node) {
        fprintf(stderr, "%s", parser_get_error_text(&parser));
        return parser_get_error(&parser);
    }
    
    err = export_to_file(node, &range, argv[1], argv[2]);

#ifdef ENABLE_GRAPHVIZ_EXPORT
    export_gv(node, "graph.dot");
#endif /* ENABLE_GRAPHVIZ_EXPORT */

    node_free(node);

    return err;
}