#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <linux/limits.h>
#include <time.h>
#include <stdbool.h>
#include <signal.h>

#include "color.h"
#include "constants.h"
#include "history.h"
#include "commands.h"

void quit_sig(int sig) {
    exit(0);
}

void change_terminal_attribute(int option) {  
    static struct termios oldt, newt;
    tcgetattr(STDIN_FILENO, &oldt);
    if (option) {
        newt = oldt;
        newt.c_lflag &= ~(ICANON | ECHO); // allows getchar without pressing enter key and echoing the character twice
        tcsetattr(STDIN_FILENO, TCSANOW, &newt); // set settings to stdin
    } else {
        tcsetattr(STDIN_FILENO, TCSANOW, &oldt); // restore to old settings
    }
}  

char **setup_path_variable() {
    char *envpath = getenv("PATH");
    char *path_cpy = malloc(sizeof(char) * (strlen(envpath) + 1));
    char *path = malloc(sizeof(char) * (strlen(envpath) + 1));
    strcpy(path_cpy, envpath);
    strcpy(path, envpath);
    int path_count = 0;
    while (*path_cpy != '\0') {
        // count number of : to count number of elements
        if (*path_cpy == ':') {
            path_count++;
        }
        path_cpy++;
    }
    path_count += 2; // adding one to be correct and one for terminator
    char **paths = malloc(sizeof(char *) * path_count);
    char *token = strtok(path, ":");
    int counter = 0;
    while (token != NULL) {
        paths[counter] = token; // set element to the pointer of start of path
        token = strtok(NULL, ":");
        counter++;
    }
    paths[counter] = NULL;
    return paths;
}

bool find_command(char **paths, char *command) {
    if (strcmp(command, "") == 0) {
        return false;
    }
    int counter = 0;
    while (*paths != NULL) {
        char current_path[PATH_MAX];
        sprintf(current_path, "%s/%s", *paths, command);
        if (access(current_path, X_OK) == 0) {
            // command is executable
            return true;
        } else {
            if (is_builtin(command)) {
                return true;
            }
        }
        paths++;
    }
    return false;
}

char *readline(char **paths) {
    int bufsize = RL_BUFSIZE;
    int position = 0;
    char *buffer = malloc(sizeof(char) * bufsize);
    int c;

    if (!buffer) {
        fprintf(stderr, "rush: Error allocating memory\n");
        exit(EXIT_FAILURE);
    }

    buffer[0] = '\0';
    while (1) {
        c = getchar(); // read a character
        int buf_len = strlen(buffer);
        if (buf_len > 0) {
            printf("\033[%ldD", strlen(buffer));  // move cursor to the beginning
            printf("\033[K"); // clear line to the right of cursor
        }
        // check each character user has input
        switch (c) {
            case EOF:
                exit(EXIT_SUCCESS);
            case 10: // enter/new line feed
                if (buf_len == 0) {
                    break;
                }
                buffer[buf_len] = '\0';
                // clear all characters after the command
                for (int start = buf_len + 1; buffer[start] != '\0'; start++) {
                    buffer[start] = '\0';
                }
                printf("%s\n", buffer); // print back the command in prompt
                save_command_history(buffer);
                return buffer;
            case 127: // backspace
                if (buf_len >= 1) {
                    buffer[buf_len - 1] = '\0'; // putting null character at last character to act as backspace
                }
                break;
            case 27: // arrow keys comes at three characters, 27, 91, then 65-68
                if (getchar() == 91) {
                    int arrow_key = getchar();
                    if (arrow_key == 65) { // up
                        // read history file and fill prompt with latest command
                        char *last_command = read_command(1);
                        if (last_command != NULL) {
                            strcpy(buffer, last_command);
                            buf_len = strlen(buffer) - 1;
                        }
                        break;
                    } else if (arrow_key == 66) { // down
                        char *last_command = read_command(0);
                        if (last_command != NULL) {
                            strcpy(buffer, last_command);
                            buf_len = strlen(buffer) - 1;
                        }
                        break;
                    } else if (arrow_key == 67) { // right
                        break;
                    } else if (arrow_key == 68) { // left
                        break;
                    }
                }
            default:
                if (c > 31 && c < 127) {
                    buffer[buf_len] = c;
                    buffer[buf_len + 1] = '\0'; // make sure printf don't print random characters
                }
        }
        char *cmd_part = strchr(buffer, ' ');
        char *command_without_arg = NULL;
        int cmd_len = 0;
        bool valid;

        if (cmd_part != NULL) {
            cmd_len = cmd_part - buffer;
            char *cmd = malloc(sizeof(char) * cmd_len + 1);
            command_without_arg = malloc(sizeof(char) * cmd_len + 1);
            if (cmd == NULL || command_without_arg == NULL) {
                fprintf(stderr, "rush: Error allocating memory\n");
                exit(EXIT_FAILURE);
            }
            for (int i = 0; i < (cmd_part - buffer); i++) {
                cmd[i] = buffer[i];
            }
            strcpy(command_without_arg, cmd);
            cmd[cmd_len] = '\0';
            command_without_arg[cmd_len] = '\0';
            valid = find_command(paths, cmd);
        } else {
            valid = find_command(paths, buffer);
        }

        if (valid) {
            if (command_without_arg != NULL) {
                buffer += cmd_len;
                printf("\x1b[38;2;137;180;250m%s\x1b[0m\x1b[38;2;255;255;255m%s\x1b[0m", command_without_arg, buffer); // print green as valid command, but only color the command, not the arguments
                buffer -= cmd_len;
            } else {
                printf("\x1b[38;2;137;180;250m%s\x1b[0m", buffer); // print green as valid command
            }
        } else {
            if (command_without_arg != NULL) {
                buffer += cmd_len;
                printf("\x1b[38;2;243;139;168m%s\x1b[0m\x1b[38;2;255;255;255m%s\x1b[0m", command_without_arg, buffer); // print green as valid command, but only color the command, not the arguments
                buffer -= cmd_len;
            } else {
                printf("\x1b[38;2;243;139;168m%s\x1b[0m", buffer); // print red as sinvalid command
            }
        }
        fflush(stdout);

        // If we have exceeded the buffer, reallocate.
        if ((buf_len + 1) >= bufsize) {
            bufsize += RL_BUFSIZE;
            buffer = realloc(buffer, bufsize);
            if (!buffer) {
                fprintf(stderr, "rush: Error allocating memory\n");
                exit(EXIT_FAILURE);
            }
        }
    }
}

// split line into arguments
char **argsplit(char *line) {
    int bufsize = TOK_BUFSIZE, position = 0;
    char **tokens = malloc(bufsize * sizeof(char*));
    char *token;

    if (!tokens) {
        fprintf(stderr, "rush: Allocation error\n");
        exit(EXIT_FAILURE);
    }

    token = strtok(line, TOK_DELIM);
    while (token != NULL) {
        tokens[position] = token;
        position++;

        if (position >= bufsize) {
            bufsize += TOK_BUFSIZE;
            tokens = realloc(tokens, bufsize * sizeof(char*));
            if (!tokens) {
                fprintf(stderr, "rush: Allocation error\n");
                exit(EXIT_FAILURE);
            }
        }

        token = strtok(NULL, TOK_DELIM);
    }
    // makes ls and diff have color without user typing it
    if (strcmp(tokens[0], "ls") == 0 || strcmp(tokens[0], "diff") == 0) {
        tokens[position] = "--color=auto";
    }
    position++;
    tokens[position] = NULL;
    return tokens;
}

// continously prompt for command and execute it
void command_loop(char **paths) {
    char *line;
    char **args;
    int status = 1;

    while (status) {
        time_t t = time(NULL);
        struct tm* current_time = localtime(&t); // get current time
        char timestr[256];
        char cwdstr[PATH_MAX];
        if (strftime(timestr, sizeof(timestr), "[%H:%M:%S]", current_time) == 0) { // format time string
            return;
        }
        if (getcwd(cwdstr, sizeof(cwdstr)) == NULL) { // get current working directory
            return;
        }
        char time[256];
        strcpy(time, timestr);
        color_text(time, lavender); // lavender colored time string
        char *cwd = malloc(sizeof(char) * PATH_MAX);
        sprintf(cwd, "[%s]", cwdstr);
        color_text(cwd, pink); // pink colored current directory
        char arrow[32] = "»";
        color_text(arrow, blue);
        printf("%s %s %s ", time, cwd, arrow);


        line = readline(paths);
        args = argsplit(line);
        status = execute(args);

        free(line);
        free(args);
        free(cwd);
    };
}

int main(int argc, char **argv) {
    // setup
    signal(SIGINT, quit_sig);
    signal(SIGTERM, quit_sig);
    signal(SIGQUIT, quit_sig);
    check_history_file();
    char **paths = setup_path_variable();
    change_terminal_attribute(1); // turn off echoing and disabling getchar requires pressing enter key to return

    command_loop(paths);

    // cleanup
    change_terminal_attribute(0); // change back to default settings
    return EXIT_SUCCESS;
}