// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "Common.h"
#include "BuildGrammar.h"
#include "Builtin.h"
#include "Parser.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define READ_SIZE 1024

static char *readStringFromFile(const char *filename)
{
    FILE *f = fopen(filename,"rb");
    if (f == NULL)
        return NULL;

    char *data = (char *)malloc(READ_SIZE);
    size_t len = 0;
    size_t r;
    while (0 < (r = fread(&data[len],1,READ_SIZE,f))) {
        len += r;
        data = (char*)realloc(data,len+READ_SIZE);
    }
    data = (char*)realloc(data,len+1);
    data[len] = '\0';
    fclose(f);
    return data;
}

static Grammar *grammarFromStr(Grammar *flatGrammar, const char *filename, const char *input)
{
    Term *term = parse(flatGrammar,"Grammar",input,0,strlen(input));
    if (term == NULL) {
        fprintf(stderr,"%s: Parse failed\n",filename);
        exit(1);
    }

    return grammarFromTerm(term,input);
}

void usage(void)
{
    printf("Usage: flat [options] GRAMMAR INPUT\n"
           "\n"
           "Options:\n"
           "\n"
           "  -b, --builtin   Use the built-in grammar instead of a user-supplied one\n"
           "  -e, --exprtree  Print expressions as trees (only relevant if -g also given)\n"
           "  -g, --grammar   Don't parse input; just show the grammar that would be used\n"
           "  -h, --help      Print this message\n"
           "\n"
           "Arguments:\n"
           "\n"
           "  GRAMMAR         A file written in the Flat syntax that defines the syntax of\n"
           "                  the language to be parsed. Should be omitted if -b is used.\n"
           "  INPUT           A file written in the syntax of the language defined by\n"
           "                  GRAMMAR. Should be omitted if -s is used.\n"
           "\n"
           "Examples:\n"
           "\n"
           "  flat -b -s      Print out the built-in grammar\n"
           "  flat arithmetic.flat test.exp\n"
           "                  Parse the file test.exp using the language defined in\n"
           "                  arithmetic.flat\n");
    exit(1);
}

char *maybeReadFile(const char *filename)
{
    if (filename == NULL)
        return NULL;
    char *str = readStringFromFile(filename);
    if (str == NULL) {
        perror(filename);
        exit(1);
    }
    return str;
}

int main(int argc, const char **argv)
{
    const char *grammarFilename = NULL;
    const char *inputFilename = NULL;
    char *grammarStr = NULL;
    char *inputStr = NULL;
    int useBuiltinGrammar = 0;
    int showGrammar = 0;
    int exprAsTree = 0;
    Grammar *builtGrammar = NULL;
    Term *inputTerm = NULL;

    for (int i = 1; i < argc; i++) {
        if (!strcmp(argv[i],"-b") || !strcmp(argv[i],"--builtin"))
            useBuiltinGrammar = 1;
        else if (!strcmp(argv[i],"-g") || !strcmp(argv[i],"--grammar"))
            showGrammar = 1;
        else if (!strcmp(argv[i],"-e") || !strcmp(argv[i],"--exprtree"))
            exprAsTree = 1;
        else if (!strcmp(argv[i],"-h") || !strcmp(argv[i],"--help"))
            usage();
        else if ((strlen(argv[i]) > 1) && argv[i][0] == '-')
            usage();
        else if ((grammarFilename == NULL) && !useBuiltinGrammar)
            grammarFilename = argv[i];
        else if ((inputFilename == NULL) && !showGrammar)
            inputFilename = argv[i];
        else
            usage();
    }

    Grammar *flatGrammar = GrammarNewBuiltin();

    inputStr = maybeReadFile(inputFilename);
    grammarStr = maybeReadFile(grammarFilename);

    if (grammarStr != NULL) {
        builtGrammar = grammarFromStr(flatGrammar,grammarFilename,grammarStr);
        if (builtGrammar == NULL) {
            fprintf(stderr,"Cannot build grammar\n");
            exit(1);
        }
    }

    Grammar *useGrammar = NULL;

    if (useBuiltinGrammar)
        useGrammar = flatGrammar;
    else if (builtGrammar != NULL)
        useGrammar = builtGrammar;
    else
        usage();

    if (inputStr != NULL) {
        const char *firstRuleName = GrammarFirstRuleName(useGrammar);
        inputTerm = parse(useGrammar,firstRuleName,inputStr,0,strlen(inputStr));
        if (inputTerm == NULL) {
            fprintf(stderr,"%s: Parse failed\n",inputFilename);
            exit(1);
        }
    }

    if (showGrammar) {
        GrammarPrint(useGrammar,exprAsTree);
    }
    else if (inputTerm != NULL) {
        TermPrint(inputTerm,inputStr,"");
    }
    else {
        usage();
    }

    free(grammarStr);
    free(inputStr);
    GrammarFree(flatGrammar);
    if (builtGrammar != NULL)
        GrammarFree(builtGrammar);
    return 0;
}