#include "parser.h"
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

void lexer_construct(Lexer* lexer, const char* text, size_t length)
{
    *lexer = (Lexer) {
        .text = text,
        .text_length = length,
        .index = 0,
        .line = 1,
        .col = 1,
    };
}

static inline bool is_id_start_char(char c)
{
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_';
}

static inline bool is_id_char(char c)
{
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
        || (c >= '0' && c <= '9') || c == '_';
}

struct MatchIdToTokenTypeCase {
    const char* keyword;
    TokenType token_type;
};

static inline TokenType match_id_to_token_type(
    const char* source, size_t length, struct MatchIdToTokenTypeCase cases[])
{
    for (size_t i = 0; cases[i].keyword != NULL; ++i) {
        if (strncmp(source, cases[i].keyword, length) == 0) {
            return cases[i].token_type;
        }
    }
    return TokenType_Id;
}

Token lexer_next(Lexer* lexer)
{
    Pos pos = lexer_pos(lexer);
    if (lexer_done(lexer)) {
        return lexer_token(lexer, TokenType_EOF, pos);
    }
    char c = lexer_current(lexer);
    if (c == ' ' || c == '\t' || c == '\n') {
        lexer_step(lexer);
        return lexer_next(lexer);
    }
    if (is_id_start_char(c)) {
        lexer_step(lexer);
        while (is_id_char(c)) {
            lexer_step(lexer);
        }
        size_t length = lexer->index - pos.index;
        TokenType token_type
            = match_id_to_token_type(&lexer->text[pos.index], length,
                (struct MatchIdToTokenTypeCase[]) {
                    { "not", TokenType_Not },
                    { "and", TokenType_And },
                    { "or", TokenType_Or },
                    { "loop", TokenType_Loop },
                    { "fn", TokenType_Fn },
                    { "return", TokenType_Return },
                    { "break", TokenType_Break },
                    { NULL, TokenType_Id },
                });
        return lexer_token(lexer, token_type, pos);
    }
    if (c >= '1' && c <= '9') {
        lexer_step(lexer);
        while (c >= '1' && c <= '9') {
            lexer_step(lexer);
        }
        return lexer_token(lexer, TokenType_Int, pos);
    }
    return lexer_token(lexer, TokenType_Error, pos);
}

Token lexer_token(Lexer* lexer, TokenType token_type, Pos pos)
{
    return (Token) {
        .token_type = token_type,
        .pos = pos,
        .length = lexer->index - pos.index,
    };
}

void lexer_step(Lexer* lexer)
{
    if (lexer_done(lexer)) {
        return;
    }
    lexer->index += 1;
    if (lexer_current(lexer) == '\n') {
        lexer->line += 1;
        lexer->col = 1;
    } else {
        lexer->col += 1;
    }
}

bool lexer_done(const Lexer* lexer)
{
    return lexer->index >= lexer->text_length;
}

char lexer_current(const Lexer* lexer) { return lexer->text[lexer->index]; }

Pos lexer_pos(const Lexer* lexer)
{
    return (Pos) {
        .index = lexer->index,
        .line = lexer->line,
        .col = lexer->col,
    };
}

int ast_node_vec_construct(ASTNodeVec* vec)
{
    const size_t capacity_start = 4;
    *vec = (ASTNodeVec) {
        .data = malloc(capacity_start),
        .length = 0,
        .capacity = capacity_start,
    };
    if (vec->data == NULL) {
        return -1;
    }
    return 0;
}

void ast_node_vec_destroy(ASTNodeVec* vec)
{
    if (vec->data != NULL) {
        free(vec->data);
    }
}

int ast_node_vec_push(ASTNodeVec* vec, ASTNode* item)
{
    if (vec->length + 1 > vec->capacity) {
        vec->capacity *= 2;
        ASTNode** data = realloc(vec->data, vec->capacity);
        if (data == NULL) {
            return -1;
        }
        vec->data = data;
    }
    vec->data[vec->length] = item;
    vec->length += 1;
    return 0;
}