#include "../Headers/slex_core.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

// Helper: Trim leading and trailing whitespace
static char* trim_whitespace(char* str) {
    while (isspace((unsigned char)*str)) {
        str++;
    }
    if (*str == '\0') {
        return str;
    }
    char* end = str + strlen(str) - 1;
    while (end > str && isspace((unsigned char)*end)) {
        end--;
    }
    *(end + 1) = '\0';
    return str;
}

// Helper: Get next line from buffer
static bool get_next_line(char** cursor, char* line_buf, int max_len) {
    char* c = *cursor;
    if (*c == '\0') return false;
    int idx = 0;
    while (*c != '\0' && *c != '\n' && *c != '\r' && idx < max_len - 1) {
        line_buf[idx++] = *c++;
    }
    line_buf[idx] = '\0';
    
    // Skip newline characters
    if (*c == '\r') c++;
    if (*c == '\n') c++;
    
    *cursor = c;
    return true;
}

bool slex_read_rule_from_cstr(char *content, slex_rules *output_rule) {
    if (!content || !output_rule) return false;

    // Initialize output structure
    output_rule->rules = NULL;
    output_rule->rule_count = 0;
    output_rule->mappings = NULL;
    output_rule->mapping_count = 0;
    output_rule->code_blocks = NULL;
    output_rule->code_block_count = 0;

    typedef enum {
        STATE_NONE,
        STATE_RULE,
        STATE_MAPPING,
        STATE_CODE
    } ParserState;

    ParserState state = STATE_NONE;
    slex_target_language current_lang = c_language;
    bool has_lang = false;

    char* cursor = content;
    char line[4096];

    while (get_next_line(&cursor, line, sizeof(line))) {
        char* trimmed = trim_whitespace(line);

        // Skip comments and empty lines
        if (trimmed[0] == '\0' || trimmed[0] == '#' || (trimmed[0] == '/' && trimmed[1] == '/')) {
            continue;
        }

        // Section switches
        if (strcmp(trimmed, "rule:") == 0) {
            state = STATE_RULE;
            continue;
        } else if (strcmp(trimmed, "mapping:") == 0) {
            state = STATE_MAPPING;
            continue;
        } else if (strcmp(trimmed, "code:") == 0) {
            state = STATE_CODE;
            continue;
        }

        if (state == STATE_RULE) {
            // Split into <Tag> and <MatchingPattern>
            // Tag is first space-delimited token
            char* tag = trimmed;
            char* pattern = trimmed;
            while (*pattern != '\0' && !isspace((unsigned char)*pattern)) {
                pattern++;
            }
            if (*pattern != '\0') {
                *pattern = '\0';
                pattern++;
                pattern = trim_whitespace(pattern);
            }

            if (strlen(tag) > 0 && strlen(pattern) > 0) {
                output_rule->rule_count++;
                output_rule->rules = (slex_rule*)realloc(output_rule->rules, output_rule->rule_count * sizeof(slex_rule));
                output_rule->rules[output_rule->rule_count - 1].Tag = strdup(tag);
                output_rule->rules[output_rule->rule_count - 1].Pattern = strdup(pattern);
            }
        } else if (state == STATE_MAPPING) {
            // Split into <Id> and <Tag>
            char* id = trimmed;
            char* tag = trimmed;
            while (*tag != '\0' && !isspace((unsigned char)*tag)) {
                tag++;
            }
            if (*tag != '\0') {
                *tag = '\0';
                tag++;
                tag = trim_whitespace(tag);
            }

            if (strlen(id) > 0 && strlen(tag) > 0) {
                output_rule->mapping_count++;
                output_rule->mappings = (slex_mapping*)realloc(output_rule->mappings, output_rule->mapping_count * sizeof(slex_mapping));
                output_rule->mappings[output_rule->mapping_count - 1].Id = strdup(id);
                output_rule->mappings[output_rule->mapping_count - 1].Tag = strdup(tag);
            }
        } else if (state == STATE_CODE) {
            int len = (int)strlen(trimmed);
            if (trimmed[0] == '%' && trimmed[len - 1] == '%') {
                // Language definition block like %c% or %c#% or %csharp%
                char lang_name[256];
                strncpy(lang_name, trimmed + 1, len - 2);
                lang_name[len - 2] = '\0';
                char* trimmed_lang = trim_whitespace(lang_name);

                if (strcmp(trimmed_lang, "c") == 0) {
                    current_lang = c_language;
                    has_lang = true;
                } else if (strcmp(trimmed_lang, "c#") == 0 || strcmp(trimmed_lang, "csharp") == 0) {
                    current_lang = csharp;
                    has_lang = true;
                } else {
                    has_lang = false;
                }
            } else if (has_lang && strcmp(trimmed, "%post_processor") == 0) {
                // Read all lines until "post_processor%"
                int cap = 4096;
                char* code = (char*)malloc(cap);
                code[0] = '\0';
                int code_len = 0;

                char code_line[4096];
                while (get_next_line(&cursor, code_line, sizeof(code_line))) {
                    char* trimmed_code = trim_whitespace(code_line);
                    if (strcmp(trimmed_code, "post_processor%") == 0) {
                        break;
                    }
                    int line_len = (int)strlen(code_line);
                    if (code_len + line_len + 2 >= cap) {
                        cap *= 2;
                        code = (char*)realloc(code, cap);
                    }
                    strcat(code, code_line);
                    strcat(code, "\n");
                    code_len += line_len + 1;
                }

                // Add or update code block
                int block_idx = -1;
                for (uint64_t i = 0; i < output_rule->code_block_count; i++) {
                    if (output_rule->code_blocks[i].target_languge == current_lang) {
                        block_idx = (int)i;
                        break;
                    }
                }

                if (block_idx == -1) {
                    output_rule->code_block_count++;
                    output_rule->code_blocks = (code_block*)realloc(output_rule->code_blocks, output_rule->code_block_count * sizeof(code_block));
                    block_idx = (int)output_rule->code_block_count - 1;
                    output_rule->code_blocks[block_idx].target_languge = current_lang;
                    output_rule->code_blocks[block_idx].post_processor_code = NULL;
                    output_rule->code_blocks[block_idx].variables = NULL;
                }
                output_rule->code_blocks[block_idx].post_processor_code = code;
            } else if (has_lang && strcmp(trimmed, "%variables") == 0) {
                // Read all lines until "variables%"
                int cap = 4096;
                char* vars = (char*)malloc(cap);
                vars[0] = '\0';
                int vars_len = 0;

                char vars_line[4096];
                while (get_next_line(&cursor, vars_line, sizeof(vars_line))) {
                    char* trimmed_vars = trim_whitespace(vars_line);
                    if (strcmp(trimmed_vars, "variables%") == 0) {
                        break;
                    }
                    int line_len = (int)strlen(vars_line);
                    if (vars_len + line_len + 2 >= cap) {
                        cap *= 2;
                        vars = (char*)realloc(vars, cap);
                    }
                    strcat(vars, vars_line);
                    strcat(vars, "\n");
                    vars_len += line_len + 1;
                }

                // Add or update code block
                int block_idx = -1;
                for (uint64_t i = 0; i < output_rule->code_block_count; i++) {
                    if (output_rule->code_blocks[i].target_languge == current_lang) {
                        block_idx = (int)i;
                        break;
                    }
                }

                if (block_idx == -1) {
                    output_rule->code_block_count++;
                    output_rule->code_blocks = (code_block*)realloc(output_rule->code_blocks, output_rule->code_block_count * sizeof(code_block));
                    block_idx = (int)output_rule->code_block_count - 1;
                    output_rule->code_blocks[block_idx].target_languge = current_lang;
                    output_rule->code_blocks[block_idx].post_processor_code = NULL;
                    output_rule->code_blocks[block_idx].variables = NULL;
                }
                output_rule->code_blocks[block_idx].variables = vars;
            }
        }
    }

    return true;
}

bool slex_read_rule_from_file(FILE *f, slex_rules *output_rule) {
    if (!f || !output_rule) return false;

    // Determine file size
    fseek(f, 0, SEEK_END);
    long size = ftell(f);
    fseek(f, 0, SEEK_SET);

    char* content = (char*)malloc(size + 1);
    if (!content) return false;

    size_t read_bytes = fread(content, 1, size, f);
    content[read_bytes] = '\0';

    bool success = slex_read_rule_from_cstr(content, output_rule);
    free(content);
    return success;
}