/*
* Copyright (c) 2017 Calvin Rose
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/

#include <stdlib.h>
#include <stdio.h>
#include <dst/dst.h>

#define DST_CLIENT_HELP 1
#define DST_CLIENT_VERBOSE 2
#define DST_CLIENT_VERSION 4
#define DST_CLIENT_REPL 8
#define DST_CLIENT_UNKNOWN 16

static Dst env;

static int client_strequal(const char *a, const char *b) {
    while (*a) if (*a++ != *b++) return 0;
    return *a == *b;
}

static int client_strequal_witharg(const char *a, const char *b) {
    while (*b) if (*a++ != *b++) return 0;
    return *a == '=';
}

/* Load source from a file */
static const uint8_t *loadsource(const char *fpath, int32_t *len) {
    FILE *f = fopen(fpath, "rb");
    long fsize;
    size_t fsizet;
    uint8_t *source = NULL;
    if (fseek(f, 0, SEEK_END)) goto error;
    fsize = ftell(f);
    if (fsize > INT32_MAX || fsize < 0) goto error;
    fsizet = fsize;
    if (fseek(f, 0, SEEK_SET)) goto error;
    if (!fsize) goto error;
    source = malloc(fsize);
    if (fread(source, 1, fsize, f) != fsizet) goto error;
    if (fclose(f)) goto error;
    *len = (int32_t) fsizet;
    return source;

    error:
    free(source);
    return NULL;
}

/* Shift bytes in buffer down */
static void bshift(DstBuffer *buf, int32_t delta) {
    buf->count -= delta;
    if (delta) {
        memmove(buf->data, buf->data + delta, buf->count);
    }
}

/* Wrap a value to add to the env */
static void set_underscore(Dst val) {
    DstTable *t = dst_table(0);
    dst_table_put(t, dst_csymbolv("value"), val);
    dst_put(env, dst_csymbolv("_"), dst_wrap_table(t));
}

/* simple repl */
static int repl() {
    DstBuffer b;
    dst_buffer_init(&b, 256);
    set_underscore(dst_wrap_nil());
    for (;;) {
        int c;
        DstParseResult res;
        DstCompileResult cres;
        DstCompileOptions opts;
        res = dst_parse(b.data, b.count);
        switch (res.status) {
            case DST_PARSE_NODATA:
                b.count = 0;
            case DST_PARSE_UNEXPECTED_EOS:
                if (b.count == 0)
                    printf("> ");
                else
                    printf(">> ");
                for (;;) {
                    c = fgetc(stdin);
                    if (c == EOF) {
                        printf("\n");
                        goto done;
                    }
                    dst_buffer_push_u8(&b, c);
                    if (c == '\n') break;
                }
                break;
            case DST_PARSE_ERROR:
                dst_puts(dst_formatc("syntax error: %S\n", res.error)); 
                b.count = 0;
                break;
            case DST_PARSE_OK:
                {
                    opts.source = res.value;
                    opts.flags = 0;
                    opts.sourcemap = res.map;
                    opts.env = env;
                    cres = dst_compile(opts);
                    if (cres.status == DST_COMPILE_OK) {
                        /*dst_puts(dst_formatc("asm: %v\n", dst_disasm(cres.funcdef)));*/
                        DstFunction *f = dst_compile_func(cres);
                        Dst ret;
                        if (dst_run(dst_wrap_function(f), &ret)) {
                            dst_puts(dst_formatc("runtime error: %S\n", dst_to_string(ret))); 
                        } else {
                            dst_puts(dst_formatc("%v\n", ret)); 
                            set_underscore(ret);
                        }
                    } else {
                        dst_puts(dst_formatc("compile error: %S\n", cres.error)); 
                    }
                    bshift(&b, res.bytes_read);
                }
                break;
        }
    }
    done:
    dst_buffer_deinit(&b);
    return 0;
}

/* Run file */
static void runfile(const uint8_t *src, int32_t len) {
    DstCompileOptions opts;
    DstCompileResult cres;
    DstParseResult res;
    const uint8_t *s = src;
    const uint8_t *end = src + len;
    while (s < end) {
        res = dst_parse(s, end - s);
        switch (res.status) {
            case DST_PARSE_NODATA:
                return;
            case DST_PARSE_UNEXPECTED_EOS:
            case DST_PARSE_ERROR:
                dst_puts(dst_formatc("syntax error at %d: %S\n",
                            s - src + res.bytes_read + 1, res.error)); 
                if (res.bytes_read == 0) {
                    s++;
                }
                break;
            case DST_PARSE_OK:
                {
                    opts.source = res.value;
                    opts.flags = 0;
                    opts.sourcemap = res.map;
                    opts.env = env;
                    cres = dst_compile(opts);
                    if (cres.status == DST_COMPILE_OK) {
                        Dst ret = dst_wrap_nil();
                        DstFunction *f = dst_compile_func(cres);
                        if (dst_run(dst_wrap_function(f), &ret)) {
                            dst_puts(dst_formatc("runtime error: %v\n", ret)); 
                        }
                    } else {
                        dst_puts(dst_formatc("compile error at %d: %S\n",
                                    s - src + cres.error_start + 1, cres.error)); 
                    }
                }
                break;
        }
        s += res.bytes_read;
    }
}

int main(int argc, char **argv) {
    int status = 0;
    int i;
    int fileRead = 0;
    uint32_t gcinterval = 0x10000;
    uint64_t flags = 0;

    /* Read the arguments. Ignore files. */
    for (i = 1; i < argc; ++i) {
        const char *arg = argv[i];
        if (*arg == '-') {
            /* Flag or option */
            if (arg[1] == '-') {
                /* Option */
                if (client_strequal(arg + 2, "help")) {
                    flags |= DST_CLIENT_HELP;
                } else if (client_strequal(arg + 2, "version")) {
                    flags |= DST_CLIENT_VERSION;
                } else if (client_strequal(arg + 2, "verbose")) {
                    flags |= DST_CLIENT_VERBOSE;
                } else if (client_strequal(arg + 2, "repl")) {
                    flags |= DST_CLIENT_REPL;
                } else if (client_strequal_witharg(arg + 2, "gcinterval")) {
                    int status = 0;
                    int32_t m;
                    const uint8_t *start = (const uint8_t *)(arg + 13);
                    const uint8_t *end = start;
                    while (*end) ++end;
                    m = dst_scan_integer(start, end - start, &status);
                    if (!status)
                        gcinterval = m;
                } else {
                    flags |= DST_CLIENT_UNKNOWN;
                }
            } else {
                /* Flag */
                const char *c = arg;
                while (*(++c)) {
                   switch (*c) {
                        case 'h':
                            flags |= DST_CLIENT_HELP;
                            break;
                        case 'v':
                            flags |= DST_CLIENT_VERSION;
                            break;
                        case 'V':
                            flags |= DST_CLIENT_VERBOSE;
                            break;
                        case 'r':
                            flags |= DST_CLIENT_REPL;
                            break;
                        default:
                            flags |= DST_CLIENT_UNKNOWN;
                            break;
                   }
                }
            }
        }
    }

    /* Handle flags and options */
    if ((flags & DST_CLIENT_HELP) || (flags & DST_CLIENT_UNKNOWN)) {
        printf( "Usage:\n"
                "%s -opts --fullopt1 --fullopt2 file1 file2...\n"
                "\n"
                "  -h      --help              Shows this information.\n"
                "  -V      --verbose           Show more output.\n"
                "  -r      --repl              Launch a repl after all files are processed.\n"
                "  -v      --version           Print the version number and exit.\n"
                "          --gcinterval=[int]  Set the amount of memory to allocate before\n"
                "                              forcing a collection in bytes. Max is 2^31-1,\n"
                "                              min is 0.\n\n",
                argv[0]);
        return 0;
    }
    if (flags & DST_CLIENT_VERSION) {
        printf("%s\n", DST_VERSION);
        return 0;
    }

    /* Set up VM */
    dst_init();
    dst_vm_gc_interval = gcinterval;
    env = dst_stl_env();
    dst_gcroot(env);

    /* Read the arguments. Only process files. */
    for (i = 1; i < argc; ++i) {
        const char *arg = argv[i];
        if (*arg != '-') {
            fileRead = 1;
            int32_t len;
            const uint8_t *s = loadsource(arg, &len);
            if (NULL == s) {
                printf("could not load file %s\n", arg);
            } else {
                runfile(s, len);
            }
        }
    }

    /* Run a repl if nothing else happened, or the flag is set */
    if (!fileRead || (flags & DST_CLIENT_REPL)) {
        status = repl();
    }

    dst_deinit();

    return status;
}