#define _POSIX_C_SOURCE 200809L
#include "repl_executor.h"
#include "repl_input.h"
#include "repl_output.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <time.h>

RavaREPLExecutor_t* rava_repl_executor_create(RavaREPLSession_t *session) {
    RavaREPLExecutor_t *executor = calloc(1, sizeof(RavaREPLExecutor_t));
    if (!executor) return NULL;
    executor->session = session;
    executor->timeout_ms = RAVA_REPL_TIMEOUT_MS;
    executor->interrupted = false;
    executor->show_timing = false;
    return executor;
}

void rava_repl_executor_destroy(RavaREPLExecutor_t *executor) {
    free(executor);
}

static char* extract_class_name(const char *code) {
    const char *p = code;
    while (*p && isspace(*p)) p++;
    if (strncmp(p, "public", 6) == 0) { p += 6; while (*p && isspace(*p)) p++; }
    if (strncmp(p, "class", 5) == 0) p += 5;
    else if (strncmp(p, "interface", 9) == 0) p += 9;
    else if (strncmp(p, "enum", 4) == 0) p += 4;
    else return NULL;
    while (*p && isspace(*p)) p++;
    const char *start = p;
    while (*p && (isalnum(*p) || *p == '_')) p++;
    if (p == start) return NULL;
    return strndup(start, p - start);
}

static char* extract_method_name(const char *code) {
    const char *paren = strchr(code, '(');
    if (!paren) return NULL;
    const char *end = paren - 1;
    while (end > code && isspace(*end)) end--;
    const char *start = end;
    while (start > code && (isalnum(*(start-1)) || *(start-1) == '_')) start--;
    if (start > end) return NULL;
    return strndup(start, end - start + 1);
}

static char* extract_method_return_type(const char *code) {
    const char *p = code;
    while (*p && isspace(*p)) p++;
    if (strncmp(p, "public", 6) == 0) { p += 6; while (*p && isspace(*p)) p++; }
    if (strncmp(p, "private", 7) == 0) { p += 7; while (*p && isspace(*p)) p++; }
    if (strncmp(p, "static", 6) == 0) { p += 6; while (*p && isspace(*p)) p++; }
    const char *start = p;
    while (*p && (isalnum(*p) || *p == '_' || *p == '[' || *p == ']')) p++;
    if (p == start) return NULL;
    return strndup(start, p - start);
}

static char* extract_var_name(const char *code) {
    const char *p = code;
    while (*p && isspace(*p)) p++;
    while (*p && (isalnum(*p) || *p == '_' || *p == '[' || *p == ']')) p++;
    while (*p && isspace(*p)) p++;
    const char *start = p;
    while (*p && (isalnum(*p) || *p == '_')) p++;
    if (p == start) return NULL;
    return strndup(start, p - start);
}

static char* extract_var_type(const char *code) {
    const char *p = code;
    while (*p && isspace(*p)) p++;
    const char *start = p;
    while (*p && (isalnum(*p) || *p == '_' || *p == '[' || *p == ']')) p++;
    if (p == start) return NULL;
    return strndup(start, p - start);
}

static char* extract_var_initializer(const char *code) {
    const char *eq = strchr(code, '=');
    if (!eq) return NULL;
    eq++;
    while (*eq && isspace(*eq)) eq++;
    const char *end = eq;
    while (*end && *end != ';') end++;
    if (end == eq) return NULL;
    while (end > eq && isspace(*(end-1))) end--;
    return strndup(eq, end - eq);
}

static char* generate_full_source(RavaREPLSession_t *session, const char *eval_code) {
    size_t capacity = 16384;
    char *source = malloc(capacity);
    if (!source) return NULL;
    size_t len = 0;
    source[0] = '\0';

#define APPEND(...) do { \
    int needed = snprintf(source + len, capacity - len, __VA_ARGS__); \
    if (needed < 0) { free(source); return NULL; } \
    while ((size_t)needed >= capacity - len) { \
        capacity *= 2; \
        char *tmp = realloc(source, capacity); \
        if (!tmp) { free(source); return NULL; } \
        source = tmp; \
        needed = snprintf(source + len, capacity - len, __VA_ARGS__); \
    } \
    len += needed; \
} while(0)

    for (size_t i = 0; i < session->class_count; i++) {
        if (session->classes[i].source) {
            APPEND("%s\n\n", session->classes[i].source);
        }
    }

    APPEND("public class _REPL_ {\n");

    for (size_t i = 0; i < session->variable_count; i++) {
        RavaREPLVariable_t *var = &session->variables[i];
        const char *type = var->type_name ? var->type_name : "int";
        APPEND("    public static %s %s", type, var->name);
        if (var->is_initialized) {
            if (var->type == RAVA_VAL_OBJECT && var->initializer) {
                APPEND(" = %s", var->initializer);
            } else {
                switch (var->type) {
                    case RAVA_VAL_INT:
                    case RAVA_VAL_LONG:
                        APPEND(" = %ld", var->value.data.int_val);
                        break;
                    case RAVA_VAL_DOUBLE:
                        APPEND(" = %g", var->value.data.double_val);
                        break;
                    case RAVA_VAL_BOOLEAN:
                        APPEND(" = %s", var->value.data.bool_val ? "true" : "false");
                        break;
                    case RAVA_VAL_STRING:
                        if (var->value.data.string_val) {
                            APPEND(" = \"%s\"", var->value.data.string_val);
                        }
                        break;
                    default:
                        if (var->initializer) {
                            APPEND(" = %s", var->initializer);
                        }
                        break;
                }
            }
        }
        APPEND(";\n");
    }

    for (size_t i = 0; i < session->method_count; i++) {
        if (session->methods[i].source) {
            APPEND("\n    public static %s\n", session->methods[i].source);
        }
    }

    APPEND("\n    public static int _eval_() {\n");
    if (eval_code && strlen(eval_code) > 0) {
        APPEND("        %s\n", eval_code);
    }
    APPEND("        return 0;\n");
    APPEND("    }\n");
    APPEND("}\n");

#undef APPEND

    return source;
}

static char* generate_expression_source(RavaREPLSession_t *session, const char *expr) {
    size_t capacity = 16384;
    char *source = malloc(capacity);
    if (!source) return NULL;
    size_t len = 0;
    source[0] = '\0';

#define APPEND(...) do { \
    int needed = snprintf(source + len, capacity - len, __VA_ARGS__); \
    if (needed < 0) { free(source); return NULL; } \
    while ((size_t)needed >= capacity - len) { \
        capacity *= 2; \
        char *tmp = realloc(source, capacity); \
        if (!tmp) { free(source); return NULL; } \
        source = tmp; \
        needed = snprintf(source + len, capacity - len, __VA_ARGS__); \
    } \
    len += needed; \
} while(0)

    for (size_t i = 0; i < session->class_count; i++) {
        if (session->classes[i].source) {
            APPEND("%s\n\n", session->classes[i].source);
        }
    }

    APPEND("public class _REPL_ {\n");

    for (size_t i = 0; i < session->variable_count; i++) {
        RavaREPLVariable_t *var = &session->variables[i];
        const char *type = var->type_name ? var->type_name : "int";
        APPEND("    public static %s %s", type, var->name);
        if (var->is_initialized) {
            if (var->type == RAVA_VAL_OBJECT && var->initializer) {
                APPEND(" = %s", var->initializer);
            } else {
                switch (var->type) {
                    case RAVA_VAL_INT:
                    case RAVA_VAL_LONG:
                        APPEND(" = %ld", var->value.data.int_val);
                        break;
                    case RAVA_VAL_DOUBLE:
                        APPEND(" = %g", var->value.data.double_val);
                        break;
                    case RAVA_VAL_BOOLEAN:
                        APPEND(" = %s", var->value.data.bool_val ? "true" : "false");
                        break;
                    case RAVA_VAL_STRING:
                        if (var->value.data.string_val) {
                            APPEND(" = \"%s\"", var->value.data.string_val);
                        }
                        break;
                    default:
                        if (var->initializer) {
                            APPEND(" = %s", var->initializer);
                        }
                        break;
                }
            }
        }
        APPEND(";\n");
    }

    for (size_t i = 0; i < session->method_count; i++) {
        if (session->methods[i].source) {
            APPEND("\n    public static %s\n", session->methods[i].source);
        }
    }

    size_t expr_len = strlen(expr);
    while (expr_len > 0 && (expr[expr_len-1] == ';' || isspace(expr[expr_len-1]))) expr_len--;
    char *clean_expr = strndup(expr, expr_len);

    char *qualified_expr = malloc(strlen(clean_expr) * 10 + 1024);
    if (!qualified_expr) {
        free(clean_expr);
        free(source);
        return NULL;
    }
    strcpy(qualified_expr, clean_expr);

    for (size_t i = 0; i < session->variable_count; i++) {
        const char *var_name = session->variables[i].name;
        size_t var_len = strlen(var_name);
        char *qualified = malloc(var_len + 8);
        snprintf(qualified, var_len + 8, "_REPL_.%s", var_name);

        char *new_expr = malloc(strlen(qualified_expr) * 10 + 1024);
        char *dst = new_expr;
        char *src = qualified_expr;

        while (*src) {
            if (strncmp(src, var_name, var_len) == 0) {
                char before = (src == qualified_expr) ? ' ' : *(src - 1);
                char after = *(src + var_len);
                if (!isalnum(before) && before != '_' && before != '.' &&
                    !isalnum(after) && after != '_') {
                    strcpy(dst, qualified);
                    dst += strlen(qualified);
                    src += var_len;
                    continue;
                }
            }
            *dst++ = *src++;
        }
        *dst = '\0';
        free(qualified_expr);
        qualified_expr = new_expr;
        free(qualified);
    }

    APPEND("\n    public static int _eval_() {\n");
    APPEND("        System.out.println(%s);\n", qualified_expr);
    APPEND("        return 0;\n");
    APPEND("    }\n");
    APPEND("}\n");

    free(clean_expr);
    free(qualified_expr);

#undef APPEND

    return source;
}

static RavaREPLExecResult_e compile_and_run(RavaREPLExecutor_t *executor, const char *source) {
    RavaREPLSession_t *session = executor->session;

    if (session->debug_mode) {
        fprintf(stderr, "[DEBUG] Compiling:\n%s\n", source);
    }

    RavaLexer_t *lexer = rava_lexer_create(source);
    RavaParser_t *parser = rava_parser_create(lexer);
    RavaASTNode_t *ast = rava_parser_parse(parser);

    if (!ast || parser->had_error) {
        rava_repl_output_error("Parse error", parser->error_message);
        rava_parser_destroy(parser);
        rava_lexer_destroy(lexer);
        return RAVA_REPL_EXEC_PARSE_ERROR;
    }

    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
    if (!rava_semantic_analyze(analyzer, ast)) {
        rava_repl_output_error("Semantic error", analyzer->error_message);
        rava_ast_node_destroy(ast);
        rava_parser_destroy(parser);
        rava_lexer_destroy(lexer);
        rava_semantic_analyzer_destroy(analyzer);
        return RAVA_REPL_EXEC_SEMANTIC_ERROR;
    }

    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);

    if (!program) {
        rava_repl_output_error("IR error", "Failed to generate bytecode");
        rava_ast_node_destroy(ast);
        rava_parser_destroy(parser);
        rava_lexer_destroy(lexer);
        rava_semantic_analyzer_destroy(analyzer);
        rava_ir_generator_destroy(ir_gen);
        return RAVA_REPL_EXEC_RUNTIME_ERROR;
    }

    RavaVM_t *vm = rava_vm_create(program);

    struct timespec start_time, end_time;
    clock_gettime(CLOCK_MONOTONIC, &start_time);

    bool success = rava_vm_execute(vm, "_REPL_", "_eval_");

    clock_gettime(CLOCK_MONOTONIC, &end_time);
    double elapsed_ms = (end_time.tv_sec - start_time.tv_sec) * 1000.0 +
                        (end_time.tv_nsec - start_time.tv_nsec) / 1000000.0;

    if (!success && vm->error_message) {
        rava_repl_output_error("Runtime error", vm->error_message);
    }

    if (executor->show_timing || elapsed_ms >= 100.0) {
        rava_repl_output_timing(elapsed_ms);
    }

    rava_vm_destroy(vm);
    rava_program_destroy(program);
    rava_ast_node_destroy(ast);
    rava_parser_destroy(parser);
    rava_lexer_destroy(lexer);
    rava_semantic_analyzer_destroy(analyzer);
    rava_ir_generator_destroy(ir_gen);

    return success ? RAVA_REPL_EXEC_SUCCESS : RAVA_REPL_EXEC_RUNTIME_ERROR;
}

static RavaValueType_e type_from_string(const char *type_name) {
    if (!type_name) return RAVA_VAL_NULL;
    if (strcmp(type_name, "int") == 0) return RAVA_VAL_INT;
    if (strcmp(type_name, "long") == 0) return RAVA_VAL_LONG;
    if (strcmp(type_name, "double") == 0) return RAVA_VAL_DOUBLE;
    if (strcmp(type_name, "float") == 0) return RAVA_VAL_FLOAT;
    if (strcmp(type_name, "boolean") == 0) return RAVA_VAL_BOOLEAN;
    if (strcmp(type_name, "char") == 0) return RAVA_VAL_CHAR;
    if (strcmp(type_name, "String") == 0) return RAVA_VAL_STRING;
    return RAVA_VAL_OBJECT;
}

static RavaValue_t parse_literal_value(const char *init, RavaValueType_e type) {
    RavaValue_t value = rava_value_null();
    if (!init) return value;

    while (*init && isspace(*init)) init++;

    switch (type) {
        case RAVA_VAL_INT:
        case RAVA_VAL_LONG:
            value.type = type;
            value.data.int_val = strtol(init, NULL, 10);
            break;
        case RAVA_VAL_DOUBLE:
        case RAVA_VAL_FLOAT:
            value.type = type;
            value.data.double_val = strtod(init, NULL);
            break;
        case RAVA_VAL_BOOLEAN:
            value.type = RAVA_VAL_BOOLEAN;
            value.data.bool_val = (strncmp(init, "true", 4) == 0);
            break;
        case RAVA_VAL_STRING:
            value.type = RAVA_VAL_STRING;
            if (init[0] == '"') {
                const char *start = init + 1;
                const char *end = strchr(start, '"');
                if (end) {
                    value.data.string_val = strndup(start, end - start);
                }
            }
            break;
        default:
            break;
    }
    return value;
}

RavaREPLExecResult_e rava_repl_executor_execute_expression(RavaREPLExecutor_t *executor, const char *code) {
    char *source = generate_expression_source(executor->session, code);
    if (!source) return RAVA_REPL_EXEC_RUNTIME_ERROR;

    RavaREPLExecResult_e result = compile_and_run(executor, source);
    free(source);
    return result;
}

RavaREPLExecResult_e rava_repl_executor_execute_statement(RavaREPLExecutor_t *executor, const char *code) {
    char *source = generate_full_source(executor->session, code);
    if (!source) return RAVA_REPL_EXEC_RUNTIME_ERROR;

    RavaREPLExecResult_e result = compile_and_run(executor, source);
    free(source);
    return result;
}

RavaREPLExecResult_e rava_repl_executor_execute_var_decl(RavaREPLExecutor_t *executor, const char *code) {
    char *var_name = extract_var_name(code);
    char *var_type = extract_var_type(code);
    char *var_init = extract_var_initializer(code);

    if (!var_name || !var_type) {
        free(var_name);
        free(var_type);
        free(var_init);
        return rava_repl_executor_execute_statement(executor, code);
    }

    RavaValueType_e type = type_from_string(var_type);
    RavaValue_t value = rava_value_null();

    if (var_init && type != RAVA_VAL_OBJECT) {
        value = parse_literal_value(var_init, type);
        value.type = type;
    } else {
        value.type = type;
        value.data.int_val = 0;
    }

    rava_repl_session_add_variable(executor->session, var_name, var_type, var_init, type, value);

    char *source = generate_full_source(executor->session, NULL);
    if (source) {
        RavaREPLExecResult_e result = compile_and_run(executor, source);
        free(source);
        if (result != RAVA_REPL_EXEC_SUCCESS) {
            free(var_name);
            free(var_type);
            free(var_init);
            return result;
        }
    }

    free(var_name);
    free(var_type);
    free(var_init);
    return RAVA_REPL_EXEC_SUCCESS;
}

RavaREPLExecResult_e rava_repl_executor_execute_method_decl(RavaREPLExecutor_t *executor, const char *code) {
    char *method_name = extract_method_name(code);
    char *return_type = extract_method_return_type(code);

    if (!method_name) {
        rava_repl_output_error("Parse error", "Could not extract method name");
        free(return_type);
        return RAVA_REPL_EXEC_PARSE_ERROR;
    }

    rava_repl_session_add_method(executor->session, method_name, return_type ? return_type : "void", code);

    char *source = generate_full_source(executor->session, NULL);
    if (!source) {
        free(method_name);
        free(return_type);
        return RAVA_REPL_EXEC_RUNTIME_ERROR;
    }

    RavaREPLExecResult_e result = compile_and_run(executor, source);
    free(source);

    if (result == RAVA_REPL_EXEC_SUCCESS) {
        printf("Method '%s' defined.\n", method_name);
    }

    free(method_name);
    free(return_type);
    return result;
}

RavaREPLExecResult_e rava_repl_executor_execute_class_decl(RavaREPLExecutor_t *executor, const char *code) {
    char *class_name = extract_class_name(code);
    if (!class_name) {
        rava_repl_output_error("Parse error", "Could not extract class name");
        return RAVA_REPL_EXEC_PARSE_ERROR;
    }

    rava_repl_session_add_class(executor->session, class_name, code);

    char *source = generate_full_source(executor->session, NULL);
    if (!source) {
        free(class_name);
        return RAVA_REPL_EXEC_RUNTIME_ERROR;
    }

    RavaREPLExecResult_e result = compile_and_run(executor, source);
    free(source);

    if (result == RAVA_REPL_EXEC_SUCCESS) {
        printf("Class '%s' defined.\n", class_name);
    }

    free(class_name);
    return result;
}

RavaREPLExecResult_e rava_repl_executor_execute(RavaREPLExecutor_t *executor, const char *code) {
    RavaREPLCodeType_e type = rava_repl_input_detect_type(code);

    switch (type) {
        case RAVA_REPL_CODE_EXPRESSION:
            return rava_repl_executor_execute_expression(executor, code);
        case RAVA_REPL_CODE_STATEMENT:
            return rava_repl_executor_execute_statement(executor, code);
        case RAVA_REPL_CODE_VAR_DECL:
            return rava_repl_executor_execute_var_decl(executor, code);
        case RAVA_REPL_CODE_METHOD_DECL:
            return rava_repl_executor_execute_method_decl(executor, code);
        case RAVA_REPL_CODE_CLASS_DECL:
            return rava_repl_executor_execute_class_decl(executor, code);
        default:
            return rava_repl_executor_execute_expression(executor, code);
    }
}

RavaValue_t rava_repl_executor_get_result(RavaREPLExecutor_t *executor) {
    return executor->last_result;
}

void rava_repl_executor_interrupt(RavaREPLExecutor_t *executor) {
    executor->interrupted = true;
}