#include "../include/parser.h"
#include "../include/bytecode.h"
#include "../include/std/hash_map.h"
#include <stdio.h>
#include <assert.h>

#define return_if_error(expr)           \
    {                                   \
        if(!(expr))                     \
            return TSL_PARSE_RESULT_ERR;\
    }

typedef struct {
    TslTokenizer tokenizer;
    TslBytecodeWriter bytecode_writer;
    TslHashMap variables;
} TslParser;

static TslParseResult tsl_parser_parse_rhs(TslParser *self, TslRegister *reg_result);
static TslParseResult tsl_parser_parse_expressions(TslParser *self, TslToken end_token);

static void tsl_parser_init(TslParser *self, const char *code, size_t code_size) {
    tsl_tokenizer_init(&self->tokenizer, code, code_size);
    tsl_bytecode_writer_init(&self->bytecode_writer);
    tsl_hash_map_init(&self->variables);
}

static void tsl_parser_deinit(TslParser *self) {
    tsl_bytecode_writer_deinit(&self->bytecode_writer);
    tsl_hash_map_deinit(&self->variables);
}

#if 0
static uint64_t hash_string_view(const void *data, size_t size) {
    uint64_t result = 0xdec05eba;
    const uint8_t *p = data;
    while(size) {
        result = ((result << 5) + result) + *p;
        ++p;
        --size;
    }
    return result;
}
#endif

static TslParseResult tsl_parser_parse_map(TslParser *self) {
    TslRegister src_reg;
    #define parse_map_element_separator                                             \
        return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_COLON));   \
        return_if_error(tsl_parser_parse_rhs(self, &src_reg));                      \
        token = tsl_tokenizer_next(&self->tokenizer);                               \
        if(token == TSL_TOKEN_COMMA) {                                              \
            continue;                                                               \
        } else if(token == TSL_TOKEN_RBRACE) {                                      \
            return TSL_PARSE_RESULT_OK;                                             \
        } else {                                                                    \
            fprintf(stderr, "Error: Expected ',' or '}', got TODO\n");              \
            return TSL_PARSE_RESULT_ERR;                                            \
        }

    for(;;) {
        TslToken token = tsl_tokenizer_next(&self->tokenizer);
        if(token == TSL_TOKEN_NUM) {
            printf("rhs num: %f\n", self->tokenizer.number_value);
            parse_map_element_separator
        } else if(token == TSL_TOKEN_BOOL) {
            printf("rhs bool: %s\n", self->tokenizer.bool_value ? "true" : "false");
            parse_map_element_separator
        } else if(token == TSL_TOKEN_NULL) {
            printf("rhs null\n");
            parse_map_element_separator
        } else if(token == TSL_TOKEN_STRING) {
            printf("rhs string: |%.*s|\n", (int)self->tokenizer.string.size, self->tokenizer.string.data);
            parse_map_element_separator
        } else if(token == TSL_TOKEN_RBRACE) {
            /* '}' after trailing ',' or an empty map */
            return TSL_PARSE_RESULT_OK;
        } else {
            fprintf(stderr, "Error: Expected '}', got TODO\n");
            return TSL_PARSE_RESULT_ERR;
        }

        token = tsl_tokenizer_next(&self->tokenizer);
    }
}

static TslParseResult tsl_parser_parse_list(TslParser *self) {
    #define parse_list_element_separator                                    \
        token = tsl_tokenizer_next(&self->tokenizer);                       \
        if(token == TSL_TOKEN_COMMA) {                                      \
            continue;                                                       \
        } else if(token == TSL_TOKEN_RBRACKET) {                            \
            return TSL_PARSE_RESULT_OK;                                     \
        } else {                                                            \
            fprintf(stderr, "Error: Expected ',' or ']', got TODO\n");      \
            return TSL_PARSE_RESULT_ERR;                                    \
        }

    for(;;) {
        /* TODO: Use tsl_parser_parse_rhs instead */
        TslToken token = tsl_tokenizer_next(&self->tokenizer);
        if(token == TSL_TOKEN_NUM) {
            printf("rhs num: %f\n", self->tokenizer.number_value);
            parse_list_element_separator
        } else if(token == TSL_TOKEN_BOOL) {
            printf("rhs bool: %s\n", self->tokenizer.bool_value ? "true" : "false");
            parse_list_element_separator
        } else if(token == TSL_TOKEN_NULL) {
            printf("rhs null\n");
            parse_list_element_separator
        } else if(token == TSL_TOKEN_STRING) {
            printf("rhs string: |%.*s|\n", (int)self->tokenizer.string.size, self->tokenizer.string.data);
            parse_list_element_separator
        } else if(token == TSL_TOKEN_RBRACKET) {
            /* ']' after trailing ',' or an empty list */
            return TSL_PARSE_RESULT_OK;
        } else {
            fprintf(stderr, "Error: Expected '}', got TODO\n");
            return TSL_PARSE_RESULT_ERR;
        }
    }
}

/* FN_BODY = '{' EXPRS '}' */
static TslParseResult tsl_parser_parse_fn_body(TslParser *self) {
    return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_LBRACE));
    return tsl_parser_parse_expressions(self, TSL_TOKEN_RBRACE);
}

/* FN = '(' (IDENTIFIER ',')* ')' FN_BODY */
static TslParseResult tsl_parser_parse_fn(TslParser *self) {
    return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_LPAREN));
    for(;;) {
        TslToken token = tsl_tokenizer_next(&self->tokenizer);
        if(token == TSL_TOKEN_RPAREN) {
            return tsl_parser_parse_fn_body(self);
        } else if(token == TSL_TOKEN_IDENTIFIER) {
            TslStringView param_name = self->tokenizer.identifier;
            printf("function parameter: |%.*s|\n", (int)param_name.size, param_name.data);
            token = tsl_tokenizer_next(&self->tokenizer);
            if(token == TSL_TOKEN_COMMA) {
                continue;
            } else if(token == TSL_TOKEN_RPAREN) {
                return tsl_parser_parse_fn_body(self);
            } else {
                fprintf(stderr, "Error: Expected ',' or ')', got TODO\n");
                return TSL_PARSE_RESULT_ERR;
            }
        } else {
            fprintf(stderr, "Error: Expected parameter name or ')', got TODO\n");
            return TSL_PARSE_RESULT_ERR;
        }
    }
}

/* VAR_INDEX = '[' RHS ']' */
static TslParseResult tsl_parser_parse_var_indexing(TslParser *self) {
    TslRegister src_reg;
    return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_LBRACKET));
    return_if_error(tsl_parser_parse_rhs(self, &src_reg));
    return tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_RBRACKET);
}

/* FUNC_CALL = '(' (RHS ',')* ')' */
static TslParseResult tsl_parser_parse_func_call(TslParser *self) {
    return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_LPAREN));
    for(;;) {
        TslToken token = tsl_tokenizer_peek(&self->tokenizer);
        if(token == TSL_TOKEN_RPAREN) {
            tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_RPAREN */
            return TSL_PARSE_RESULT_OK;
        } else {
            TslRegister src_reg;
            return_if_error(tsl_parser_parse_rhs(self, &src_reg));
            token = tsl_tokenizer_next(&self->tokenizer);
            if(token == TSL_TOKEN_COMMA) {
                continue;
            } else if(token == TSL_TOKEN_RPAREN) {
                return TSL_PARSE_RESULT_OK;
            } else {
                fprintf(stderr, "Error: Expected ',' or ')', got TODO\n");
                return TSL_PARSE_RESULT_ERR;
            }
        }
    }
}

/* TODO: Do not allow empty command */
/* TODO: Allow command inside another command */
/* COMMAND = TODO */
static TslParseResult tsl_parser_parse_command(TslParser *self) {
    return_if_error(tsl_tokenizer_accept(&self->tokenizer, TSL_TOKEN_LPAREN));
    for(;;) {
        TslStringView command_arg;
        TslCommandToken command_token = tsl_tokenizer_next_command_arg(&self->tokenizer, &command_arg);
        if(command_token == TSL_COMMAND_TOKEN_ARG) {
            printf("command arg: |%.*s|\n", (int)command_arg.size, command_arg.data);
        } else if(command_token == TSL_COMMAND_TOKEN_END) {
            return TSL_PARSE_RESULT_OK;
        } else {
            fprintf(stderr, "Error: Expected command argument or ')', got TODO\n");
            return TSL_PARSE_RESULT_ERR;
        }
    }
}

/* RHS_SUB = (VAR_INDEX|FUNC_CALL RHS_SUB?)|(TOKEN_ARITHMETIC RHS) */
static TslParseResult tsl_parser_parse_rhs_sub(TslParser *self) {
    TslToken token = tsl_tokenizer_peek(&self->tokenizer);
    if(token == TSL_TOKEN_LBRACKET) {
        return_if_error(tsl_parser_parse_var_indexing(self));
        return tsl_parser_parse_rhs_sub(self);
    } else if(token == TSL_TOKEN_LPAREN) {
        return_if_error(tsl_parser_parse_func_call(self));
        return tsl_parser_parse_rhs_sub(self);
    } else if(token == TSL_TOKEN_ARITHMETIC) {
        TslRegister src_reg;
        tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_ARITHMETIC */
        printf("rhs sub arithmetic symbol: %c\n", self->tokenizer.arithmetic_symbol);
        /* TODO: Handle arithmetic expression precedence */
        return tsl_parser_parse_rhs(self, &src_reg);
    }
    /*
        No sub expression found, possibly a new expression after this (a new expression on a new line), let that
        part of the code handle error if there is any instead.
    */
    return TSL_PARSE_RESULT_OK;
}

/* RHS_SUB_ARITHMETIC = TOKEN_ARITHMETIC RHS */
static TslParseResult tsl_parser_parse_rhs_sub_arithmetic(TslParser *self) {
    TslToken token = tsl_tokenizer_peek(&self->tokenizer);
    if(token == TSL_TOKEN_ARITHMETIC) {
        TslRegister src_reg;
        tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_ARITHMETIC */
        printf("rhs sub arithmetic symbol: %c\n", self->tokenizer.arithmetic_symbol);
        /* TODO: Handle arithmetic expression precedence */
        return tsl_parser_parse_rhs(self, &src_reg);
    }
    /*
        No sub expression found, possibly a new expression after this (a new expression on a new line), let that
        part of the code handle error if there is any instead.
    */
    return TSL_PARSE_RESULT_OK;
}

/* RHS = (IDENTIFIER|NUM|BOOL|NULL|STRING|MAP|LIST|('fn' FN)|('$' COMMAND)) RHS_SUB? */
TslParseResult tsl_parser_parse_rhs(TslParser *self, TslRegister *reg_result) {
    TslToken token = tsl_tokenizer_next(&self->tokenizer);
    if(token == TSL_TOKEN_IDENTIFIER) {
        TslStringView var_name = self->tokenizer.identifier;
        assert(0 && "TODO: Implement");
        printf("rhs var: %.*s\n", (int)var_name.size, var_name.data);
        return tsl_parser_parse_rhs_sub(self);
    } else if(token == TSL_TOKEN_NUM) {
        *reg_result = tsl_bytecode_writer_get_unique_register(&self->bytecode_writer);
        if(*reg_result == -1) {
            fprintf(stderr, "Error: Too many registers used\n");
            return TSL_PARSE_RESULT_ERR;
        }

        return_if_error(tsl_bytecode_writer_load_number(&self->bytecode_writer, *reg_result, self->tokenizer.number_value));
        printf("rhs num: %f\n", self->tokenizer.number_value);
        return tsl_parser_parse_rhs_sub_arithmetic(self);
    } else if(token == TSL_TOKEN_BOOL) {
        assert(0 && "TODO: Implement");
        printf("rhs bool: %s\n", self->tokenizer.bool_value ? "true" : "false");
    } else if(token == TSL_TOKEN_NULL) {
        assert(0 && "TODO: Implement");
        printf("rhs null\n");
    } else if(token == TSL_TOKEN_STRING) {
        assert(0 && "TODO: Implement");
        printf("rhs string: |%.*s|\n", (int)self->tokenizer.string.size, self->tokenizer.string.data);
    } else if(token == TSL_TOKEN_LBRACE) {
        assert(0 && "TODO: Implement");
        return tsl_parser_parse_map(self);
    } else if(token == TSL_TOKEN_LBRACKET) {
        assert(0 && "TODO: Implement");
        return tsl_parser_parse_list(self);
    } else if(token == TSL_TOKEN_FN) {
        assert(0 && "TODO: Implement");
        return tsl_parser_parse_fn(self);
    } else if(token == TSL_TOKEN_DOLLAR_SIGN) {
        assert(0 && "TODO: Implement");
        return tsl_parser_parse_command(self);
    } else {
        fprintf(stderr, "Error: Expected variable, number, bool, null, map, list, function or command, got TODO (%d) (line: %d)\n", token, tsl_tokenizer_get_line_by_index(&self->tokenizer, self->tokenizer.prev_code_index));
        return TSL_PARSE_RESULT_ERR;
    }
    return TSL_PARSE_RESULT_OK;
}

/*
    EXPR = IDENTIFIER ('=' RHS)|RHS_SUB
    EXPRS = EXPR*
*/
TslParseResult tsl_parser_parse_expressions(TslParser *self, TslToken end_token) {
    for(;;) {
        TslToken token = tsl_tokenizer_next(&self->tokenizer);
        if(token == TSL_TOKEN_IDENTIFIER) {
            TslStringView identifier = self->tokenizer.identifier;
            printf("identifier: %.*s\n", (int)identifier.size, identifier.data);
            if(tsl_tokenizer_peek(&self->tokenizer) == TSL_TOKEN_EQUAL) {
                TslRegister dst_reg;
                TslRegister src_reg;

                tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_EQUAL */
                return_if_error(tsl_parser_parse_rhs(self, &src_reg));

                dst_reg = tsl_bytecode_writer_get_unique_register(&self->bytecode_writer);
                if(dst_reg < 0)
                    return TSL_PARSE_RESULT_ERR;
                return_if_error(tsl_bytecode_writer_mov_reg(&self->bytecode_writer, dst_reg, src_reg));
            } else {
                return_if_error(tsl_parser_parse_rhs_sub(self));
            }
        } else if(token == end_token) {
            break;
        } else {
            fprintf(stderr, "Error: Expected identifier, got TODO\n");
            return TSL_PARSE_RESULT_ERR;
        }
    }
    return TSL_PARSE_RESULT_OK;
}

TslParseResult tsl_parse(const char *code, size_t code_size) {
    TslParseResult result;
    TslParser parser;
    tsl_parser_init(&parser, code, code_size);
    result = tsl_parser_parse_expressions(&parser, TSL_TOKEN_END_OF_FILE);
    tsl_parser_deinit(&parser);
    return result;
}