/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2011 Amaury Pouly
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include <stdio.h>
#include <ctype.h>
#include <stdint.h>
#include "dbparser.h"

typedef uint8_t byte;

extern bool g_debug;
extern void *xmalloc(size_t s);
extern int convxdigit(char digit, byte *val);

#define bug(...) do { fprintf(stderr, __VA_ARGS__); exit(1); } while(0)
#define bugp(...) do { fprintf(stderr, __VA_ARGS__); perror(" "); exit(1); } while(0)

enum lexem_type_t
{
    LEX_IDENTIFIER,
    LEX_LPAREN,
    LEX_RPAREN,
    LEX_NUMBER,
    LEX_STRING, /* double-quoted string */
    LEX_EQUAL,
    LEX_SEMICOLON,
    LEX_LBRACE,
    LEX_RBRACE,
    LEX_RANGLE,
    LEX_EOF
};

struct lexem_t
{
    enum lexem_type_t type;
    char *str;
    uint32_t num;
    int line;
    const char *file;
};

struct context_t
{
    const char *file;
    char *begin;
    char *end;
    char *ptr;
    int line;
};

#define parse_error(ctx, ...) \
    do { fprintf(stderr, "%s:%d: ", ctx->file, ctx->line); \
        fprintf(stderr, __VA_ARGS__); exit(2); } while(0)

static void advance(struct context_t *ctx, int nr_chars)
{
    while(nr_chars--)
    {
        if(*(ctx->ptr++) == '\n')
            ctx->line++;
    }
}

static inline bool eof(struct context_t *ctx)
{
    return ctx->ptr == ctx->end;
}

static inline bool next_valid(struct context_t *ctx, int nr)
{
    return ctx->ptr + nr < ctx->end;
}

static inline char cur_char(struct context_t *ctx)
{
    return *ctx->ptr;
}

static inline char next_char(struct context_t *ctx, int nr)
{
    return ctx->ptr[nr];
}

static inline void locate_lexem(struct lexem_t *lex, struct context_t *ctx)
{
    lex->file = ctx->file;
    lex->line = ctx->line;
}

static void __parse_string(struct context_t *ctx, void *user, void (*emit_fn)(void *user, char c))
{
    while(!eof(ctx))
    {
        if(cur_char(ctx) == '"')
            break;
        else if(cur_char(ctx) == '\\')
        {
            advance(ctx, 1);
            if(eof(ctx))
                parse_error(ctx, "Unfinished string\n");
            if(cur_char(ctx) == '\\') emit_fn(user, '\\');
            else if(cur_char(ctx) == '\'') emit_fn(user, '\'');
            else if(cur_char(ctx) == '\"') emit_fn(user, '\"');
            else parse_error(ctx, "Unknown escape sequence \\%c\n", cur_char(ctx));
            advance(ctx, 1);
        }
        else
        {
            emit_fn(user, cur_char(ctx));
            advance(ctx, 1);
        }
    }
    if(eof(ctx) || cur_char(ctx) != '"')
        parse_error(ctx, "Unfinished string\n");
    advance(ctx, 1);
}

static void __parse_string_emit(void *user, char c)
{
    char **pstr = (char **)user;
    *(*pstr)++ = c;
}

static void __parse_string_count(void *user, char c)
{
    (void) c;
    (*(int *)user)++;
}

static void parse_string(struct context_t *ctx, struct lexem_t *lexem)
{
    locate_lexem(lexem, ctx);
    /* skip " */
    advance(ctx, 1);
    /* compute length */
    struct context_t cpy_ctx = *ctx;
    int length = 0;
    __parse_string(&cpy_ctx, (void *)&length, __parse_string_count);
    /* parse again */
    lexem->type = LEX_STRING;
    lexem->str = xmalloc(length + 1);
    lexem->str[length] = 0;
    char *pstr = lexem->str;
    __parse_string(ctx, (void *)&pstr, __parse_string_emit);
}

static void parse_ascii_number(struct context_t *ctx, struct lexem_t *lexem)
{
    locate_lexem(lexem, ctx);
    /* skip ' */
    advance(ctx, 1);
    /* we expect n<=4 character and then '  */
    int len = 0;
    uint32_t value = 0;
    while(!eof(ctx))
    {
        if(cur_char(ctx) != '\'')
        {
            value = value << 8 | cur_char(ctx);
            len++;
            advance(ctx, 1);
        }
        else
            break;
    }
    if(eof(ctx) || cur_char(ctx) != '\'')
        parse_error(ctx, "Unterminated ascii number literal\n");
    if(len == 0 || len > 4)
        parse_error(ctx, "Invalid ascii number literal length: only 1 to 4 characters allowed\n");
    /* skip ' */
    advance(ctx, 1);
    lexem->type = LEX_NUMBER;
    lexem->num = value;
}

static void parse_number(struct context_t *ctx, struct lexem_t *lexem)
{
    locate_lexem(lexem, ctx);
    /* check base */
    int base = 10;
    if(cur_char(ctx) == '0' && next_valid(ctx, 1) && next_char(ctx, 1) == 'x')
    {
        advance(ctx, 2);
        base = 16;
    }

    lexem->type = LEX_NUMBER;
    lexem->num = 0;
    while(!eof(ctx) && isxdigit(cur_char(ctx)))
    {
        if(base == 10 && !isdigit(cur_char(ctx)))
            break;
        byte v;
        if(convxdigit(cur_char(ctx), &v))
            break;
        lexem->num = base * lexem->num + v;
        advance(ctx, 1);
    }
}

static void parse_identifier(struct context_t *ctx, struct lexem_t *lexem)
{
    locate_lexem(lexem, ctx);
    /* remember position */
    char *old = ctx->ptr;
    while(!eof(ctx) && (isalnum(cur_char(ctx)) || cur_char(ctx) == '_'))
        advance(ctx, 1);
    lexem->type = LEX_IDENTIFIER;
    int len = ctx->ptr - old;
    lexem->str = xmalloc(len + 1);
    lexem->str[len] = 0;
    memcpy(lexem->str, old, len);
}

static void next_lexem(struct context_t *ctx, struct lexem_t *lexem)
{
    #define ret_simple(t, adv) \
        do {locate_lexem(lexem, ctx); \
            lexem->type = t; \
            advance(ctx, adv); \
            return;} while(0)
    while(!eof(ctx))
    {
        char c = cur_char(ctx);
        /* skip whitespace */
        if(c == ' ' || c == '\t' || c == '\n' || c == '\r')
        {
            advance(ctx, 1);
            continue;
        }
        /* skip C++ style comments */
        if(c == '/' && next_valid(ctx, 1) && next_char(ctx, 1) == '/')
        {
            while(!eof(ctx) && cur_char(ctx) != '\n')
                advance(ctx, 1);
            continue;
        }
        /* skip C-style comments */
        if(c == '/' && next_valid(ctx, 1) && next_char(ctx, 1) == '*')
        {
            advance(ctx, 2);
            while(true)
            {
                if(!next_valid(ctx, 1))
                    parse_error(ctx, "Unterminated comment");
                if(cur_char(ctx) == '*' && next_char(ctx, 1) == '/')
                {
                    advance(ctx, 2);
                    break;
                }
                advance(ctx, 1);
            }
            continue;
        }
        break;
    }
    if(eof(ctx)) ret_simple(LEX_EOF, 0);
    char c = cur_char(ctx);
    if(c == '(') ret_simple(LEX_LPAREN, 1);
    if(c == ')') ret_simple(LEX_RPAREN, 1);
    if(c == '{') ret_simple(LEX_LBRACE, 1);
    if(c == '}') ret_simple(LEX_RBRACE, 1);
    if(c == '>') ret_simple(LEX_RANGLE, 1);
    if(c == '=') ret_simple(LEX_EQUAL, 1);
    if(c == ';') ret_simple(LEX_SEMICOLON, 1);
    if(c == '"') return parse_string(ctx, lexem);
    if(c == '\'') return parse_ascii_number(ctx, lexem);
    if(isdigit(c)) return parse_number(ctx, lexem);
    if(isalpha(c) || c == '_') return parse_identifier(ctx, lexem);
    parse_error(ctx, "Unexpected character '%c'\n", c);
    #undef ret_simple
}

#if 0
static void log_lexem(struct lexem_t *lexem)
{
    switch(lexem->type)
    {
        case LEX_EOF: printf("<eof>"); break;
        case LEX_EQUAL: printf("="); break;
        case LEX_IDENTIFIER: printf("id(%s)", lexem->str); break;
        case LEX_LPAREN: printf("("); break;
        case LEX_RPAREN: printf(")"); break;
        case LEX_LBRACE: printf("{"); break;
        case LEX_RBRACE: printf("}"); break;
        case LEX_SEMICOLON: printf(";"); break;
        case LEX_NUMBER: printf("num(%d)", lexem->num); break;
        case LEX_STRING: printf("str(%s)", lexem->str); break;
        default: printf("<unk>");
    }
}
#endif

struct cmd_source_t *db_find_source_by_id(struct cmd_file_t *cmd_file, const char *id)
{
    struct cmd_source_t *src = cmd_file->source_list;
    while(src)
    {
        if(strcmp(src->identifier, id) == 0)
            return src;
        src = src->next;
    }
    return NULL;
}

static void generate_default_version(struct sb_version_t *ver)
{
    ver->major = 0x999;
    ver->minor = 0x999;
    ver->revision = 0x999;
}

#define INVALID_SB_SUBVERSION   0xffff

static uint16_t parse_sb_subversion(char *str)
{
    int len = strlen(str);
    uint16_t n = 0;
    if(len == 0 || len > 4)
        return INVALID_SB_SUBVERSION;
    for(int i = 0; i < len; i++)
    {
        if(!isdigit(str[i]))
            return INVALID_SB_SUBVERSION;
        n = n << 4 | (str[i] - '0');
    }
    return n;
}

bool db_parse_sb_version(struct sb_version_t *ver, char *str)
{
    int len = strlen(str);
    int cnt = 0;
    int pos[2];

    for(int i = 0; i < len; i++)
    {
        if(str[i] != '.')
            continue;
        if(cnt == 2)
            return false;
        pos[cnt++] = i + 1;
        str[i] = 0;
    }
    if(cnt != 2)
        return false;
    ver->major = parse_sb_subversion(str);
    ver->minor = parse_sb_subversion(str + pos[0]);
    ver->revision = parse_sb_subversion(str + pos[1]);
    return ver->major != INVALID_SB_SUBVERSION &&
        ver->minor != INVALID_SB_SUBVERSION &&
        ver->revision != INVALID_SB_SUBVERSION;
}

#undef parse_error
#define parse_error(lexem, ...) \
    do { fprintf(stderr, "%s:%d: ", lexem.file, lexem.line); \
        fprintf(stderr, __VA_ARGS__); exit(2); } while(0)

struct cmd_file_t *db_parse_file(const char *file)
{
    size_t size;
    FILE *f = fopen(file, "r");
    if(f == NULL)
        bugp("Cannot open file '%s'", file);
    fseek(f, 0, SEEK_END);
    size = ftell(f);
    fseek(f, 0, SEEK_SET);
    char *buf = xmalloc(size);
    if(fread(buf, size, 1, f) != 1)
        bugp("Cannot read file '%s'", file);
    fclose(f);

    if(g_debug)
        printf("Parsing db file '%s'\n", file);
    struct cmd_file_t *cmd_file = xmalloc(sizeof(struct cmd_file_t));
    memset(cmd_file, 0, sizeof(struct cmd_file_t));

    generate_default_version(&cmd_file->product_ver);
    generate_default_version(&cmd_file->component_ver);

    struct lexem_t lexem;
    struct context_t ctx;
    ctx.file = file;
    ctx.line = 1;
    ctx.begin = buf;
    ctx.ptr = buf;
    ctx.end = buf + size;
    #define next() next_lexem(&ctx, &lexem)
    /* init lexer */
    next();
    /* options ? */
    if(lexem.type == LEX_IDENTIFIER && !strcmp(lexem.str, "options"))
    {
        next();
        if(lexem.type != LEX_LBRACE)
            parse_error(lexem, "'{' expected after 'options'\n");

        while(true)
        {
            next();
            if(lexem.type == LEX_RBRACE)
                break;
            if(lexem.type != LEX_IDENTIFIER)
                parse_error(lexem, "Identifier expected in options\n");
            char *opt = lexem.str;
            next();
            if(lexem.type != LEX_EQUAL)
                parse_error(lexem, "'=' expected after identifier\n");
            next();
            if(!strcmp(opt, "productVersion") || !strcmp(opt, "componentVersion"))
            {
                if(lexem.type != LEX_STRING)
                    parse_error(lexem, "String expected after '='\n");
                bool ret;
                if(!strcmp(opt, "productVersion"))
                    ret = db_parse_sb_version(&cmd_file->product_ver, lexem.str);
                else
                    ret = db_parse_sb_version(&cmd_file->component_ver, lexem.str);
                if(!ret)
                    parse_error(lexem, "Invalid product/component version");
            }
            else
                parse_error(lexem, "Unknown option '%s'\n", opt);
            next();
            if(lexem.type != LEX_SEMICOLON)
               parse_error(lexem, "';' expected after string\n");
        }
        next();
    }
    /* sources */
    if(lexem.type != LEX_IDENTIFIER || strcmp(lexem.str, "sources"))
        parse_error(lexem, "'sources' expected\n");
    next();
    if(lexem.type != LEX_LBRACE)
        parse_error(lexem, "'{' expected after 'sources'\n");

    while(true)
    {
        next();
        if(lexem.type == LEX_RBRACE)
            break;
        struct cmd_source_t *src = xmalloc(sizeof(struct cmd_source_t));
        memset(src, 0, sizeof(struct cmd_source_t));
        src->next = cmd_file->source_list;
        if(lexem.type != LEX_IDENTIFIER)
            parse_error(lexem, "identifier expected in sources\n");
        src->identifier = lexem.str;
        next();
        if(lexem.type != LEX_EQUAL)
            parse_error(lexem, "'=' expected after identifier\n");
        next();
        if(lexem.type != LEX_STRING)
            parse_error(lexem, "String expected after '='\n");
        src->filename = lexem.str;
        next();
        if(lexem.type != LEX_SEMICOLON)
            parse_error(lexem, "';' expected after string\n");
        if(db_find_source_by_id(cmd_file, src->identifier) != NULL)
            parse_error(lexem, "Duplicate source identifier\n");
        /* type filled later */
        src->type = CMD_SRC_UNK;
        cmd_file->source_list = src;
    }

    /* sections */
    struct cmd_section_t *end_sec = NULL;
    while(true)
    {
        struct cmd_section_t *sec = xmalloc(sizeof(struct cmd_section_t));
        struct cmd_inst_t *end_list = NULL;
        memset(sec, 0, sizeof(struct cmd_section_t));
        next();
        if(lexem.type == LEX_EOF)
            break;
        if(lexem.type != LEX_IDENTIFIER || strcmp(lexem.str, "section") != 0)
            parse_error(lexem, "'section' expected\n");
        next();
        if(lexem.type != LEX_LPAREN)
            parse_error(lexem, "'(' expected after 'section'\n");
        next();
        /* can be a number or a 4 character long string */
        if(lexem.type == LEX_NUMBER)
        {
            sec->identifier = lexem.num;
        }
        else
            parse_error(lexem, "Number expected as section identifier\n");
        
        next();
        if(lexem.type != LEX_RPAREN)
            parse_error(lexem, "')' expected after section identifier\n");
        next();
        if(lexem.type != LEX_LBRACE)
            parse_error(lexem, "'{' expected after section directive\n");
        /* commands */
        while(true)
        {
            struct cmd_inst_t *inst = xmalloc(sizeof(struct cmd_inst_t));
            memset(inst, 0, sizeof(struct cmd_inst_t));
            next();
            if(lexem.type == LEX_RBRACE)
                break;
            if(lexem.type != LEX_IDENTIFIER)
                parse_error(lexem, "Instruction expected in section\n");
            if(strcmp(lexem.str, "load") == 0)
                inst->type = CMD_LOAD;
            else if(strcmp(lexem.str, "call") == 0)
                inst->type = CMD_CALL;
            else if(strcmp(lexem.str, "jump") == 0)
                inst->type = CMD_JUMP;
            else if(strcmp(lexem.str, "mode") == 0)
                inst->type = CMD_MODE;
            else
                parse_error(lexem, "Instruction expected in section\n");
            next();

            if(inst->type == CMD_LOAD)
            {
                if(lexem.type != LEX_IDENTIFIER)
                    parse_error(lexem, "Identifier expected after instruction\n");
                inst->identifier = lexem.str;
                if(db_find_source_by_id(cmd_file, inst->identifier) == NULL)
                    parse_error(lexem, "Undefined reference to source '%s'\n", inst->identifier);
                next();
                if(lexem.type == LEX_RANGLE)
                {
                    // load at
                    inst->type = CMD_LOAD_AT;
                    next();
                    if(lexem.type != LEX_NUMBER)
                        parse_error(lexem, "Number expected for loading address\n");
                    inst->addr = lexem.num;
                    next();
                }
                if(lexem.type != LEX_SEMICOLON)
                    parse_error(lexem, "';' expected after command\n");
            }
            else if(inst->type == CMD_CALL || inst->type == CMD_JUMP)
            {
                if(lexem.type == LEX_IDENTIFIER)
                {
                    inst->identifier = lexem.str;
                    if(db_find_source_by_id(cmd_file, inst->identifier) == NULL)
                        parse_error(lexem, "Undefined reference to source '%s'\n", inst->identifier);
                    next();
                }
                else if(lexem.type == LEX_NUMBER)
                {
                    inst->type = (inst->type == CMD_CALL) ? CMD_CALL_AT : CMD_JUMP_AT;
                    inst->addr = lexem.num;
                    next();
                }
                else
                    parse_error(lexem, "Identifier or number expected after jump/load\n");
                
                if(lexem.type == LEX_LPAREN)
                {
                    next();
                    if(lexem.type != LEX_NUMBER)
                        parse_error(lexem, "Expected numeral expression after (\n");
                    inst->argument = lexem.num;
                    next();
                    if(lexem.type != LEX_RPAREN)
                        parse_error(lexem, "Expected closing brace\n");
                    next();
                }
                if(lexem.type != LEX_SEMICOLON)
                    parse_error(lexem, "Expected ';' after command\n");
            }
            else if(inst->type == CMD_MODE)
            {
                if(lexem.type != LEX_NUMBER)
                    parse_error(lexem, "Number expected after 'mode'\n");
                inst->argument = lexem.num;
                next();
                if(lexem.type != LEX_SEMICOLON)
                    parse_error(lexem, "Expected ';' after command\n");
            }
            else
                parse_error(lexem, "Internal error");
            if(end_list == NULL)
            {
                sec->inst_list = inst;
                end_list = inst;
            }
            else
            {
                end_list->next = inst;
                end_list = inst;
            }
        }

        if(end_sec == NULL)
        {
            cmd_file->section_list = sec;
            end_sec = sec;
        }
        else
        {
            end_sec->next = sec;
            end_sec = sec;
        }
    }
    #undef next

    return cmd_file;
}