#define _POSIX_C_SOURCE 200809L
#include "repl.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <signal.h>
#include <unistd.h>
#include <readline/readline.h>
#include <readline/history.h>

static volatile bool g_interrupted = false;

static void sigint_handler(int sig) {
    (void)sig;
    g_interrupted = true;
}

RavaREPL_t* rava_repl_create(void) {
    RavaREPL_t *repl = calloc(1, sizeof(RavaREPL_t));
    if (!repl) return NULL;

    repl->session = rava_repl_session_create();
    if (!repl->session) {
        free(repl);
        return NULL;
    }

    repl->input = rava_repl_input_create();
    if (!repl->input) {
        rava_repl_session_destroy(repl->session);
        free(repl);
        return NULL;
    }

    repl->executor = rava_repl_executor_create(repl->session);
    if (!repl->executor) {
        rava_repl_input_destroy(repl->input);
        rava_repl_session_destroy(repl->session);
        free(repl);
        return NULL;
    }

    repl->running = true;
    repl->interactive = true;

    return repl;
}

void rava_repl_destroy(RavaREPL_t *repl) {
    if (!repl) return;
    rava_repl_executor_destroy(repl->executor);
    rava_repl_input_destroy(repl->input);
    rava_repl_session_destroy(repl->session);
    free(repl);
}

void rava_repl_print_banner(void) {
    printf("Rava %s Interactive Interpreter\n", RAVA_REPL_VERSION);
    printf("Type \"%%help\" for commands, \"%%quit\" to exit\n\n");
}

void rava_repl_print_prompt(RavaREPL_t *repl, bool continuation) {
    (void)repl;
    printf("%s", continuation ? "... " : ">>> ");
    fflush(stdout);
}

bool rava_repl_process_line(RavaREPL_t *repl, const char *line) {
    if (!repl || !line) return true;

    while (*line && isspace(*line)) line++;
    if (strlen(line) == 0) return true;

    if (rava_repl_command_is_command(line)) {
        char *arg = NULL;
        RavaREPLCommand_e cmd = rava_repl_command_parse(line, &arg);

        if (cmd == RAVA_CMD_QUIT) {
            free(arg);
            return false;
        }

        rava_repl_history_add(repl->session->history, line);
        bool result = rava_repl_command_execute(repl->session, cmd, arg);
        free(arg);
        return result;
    }

    RavaREPLInputState_e state = rava_repl_input_append(repl->input, line);

    if (state == RAVA_REPL_INPUT_COMPLETE) {
        const char *code = rava_repl_input_get(repl->input);
        rava_repl_history_add(repl->session->history, code);
        rava_repl_executor_execute(repl->executor, code);
        rava_repl_input_reset(repl->input);
    } else if (state == RAVA_REPL_INPUT_ERROR) {
        rava_repl_output_error("Input error", "Buffer overflow or invalid input");
        rava_repl_input_reset(repl->input);
    }

    return true;
}

static char* read_line_stdin(const char *prompt) {
    printf("%s", prompt);
    fflush(stdout);

    char *line = NULL;
    size_t len = 0;
    ssize_t read = getline(&line, &len, stdin);

    if (read == -1) {
        free(line);
        return NULL;
    }

    if (read > 0 && line[read - 1] == '\n') {
        line[read - 1] = '\0';
    }

    return line;
}

int rava_repl_run(void) {
    struct sigaction sa;
    sa.sa_handler = sigint_handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sigaction(SIGINT, &sa, NULL);

    RavaREPL_t *repl = rava_repl_create();
    if (!repl) {
        fprintf(stderr, "Failed to create REPL\n");
        return 1;
    }

    bool is_tty = isatty(fileno(stdin));

    rava_repl_print_banner();

    char history_file[256];
    const char *home = getenv("HOME");
    if (home && is_tty) {
        snprintf(history_file, sizeof(history_file), "%s/.rava_history", home);
        rava_repl_history_load(repl->session->history, history_file);
        read_history(history_file);
    }

    if (is_tty) {
        rl_bind_key('\t', rl_complete);
    }

    while (repl->running) {
        bool continuation = !rava_repl_input_is_empty(repl->input);
        const char *prompt = continuation ? "... " : ">>> ";

        char *line;
        if (is_tty) {
            line = readline(prompt);
        } else {
            line = read_line_stdin(prompt);
        }

        if (!line) {
            if (is_tty) printf("\n");
            break;
        }

        if (strlen(line) == 0) {
            free(line);
            continue;
        }

        if (is_tty && strlen(line) > 0) {
            add_history(line);
        }

        g_interrupted = false;
        repl->running = rava_repl_process_line(repl, line);

        free(line);
    }

    if (home && is_tty) {
        rava_repl_history_save(repl->session->history, history_file);
        write_history(history_file);
    }

    rava_repl_destroy(repl);
    return 0;
}