#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>

#include "action_list.h"
#include "file.h"
#include "myers.h"
#include "utilities.h"
#include "tree.h"

static void usage(int exitcode) {
    printf("usage: merk <command> [<args>]\n\n  init     Initializes a repository in the current directory\n  diff     Displays the difference between the given two files\n  status   Displays a list of modified and untracked files in the repository\n");
    exit(exitcode);
}

int main(int argc, char **argv) {
    if (argc == 2 && (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help"))) {
        usage(0);
    }

    const char* subcmd = argv[1];

    if (strcmp(subcmd, "diff") != 0 && strcmp(subcmd, "init") != 0 && strcmp(subcmd, "status") != 0) {
        fprintf(stderr, "ERROR: Unknown subcommand: '%s'\n", subcmd);
        usage(2);
    }

    // Initializes a merk repository in the current directory
    if (strcmp(subcmd, "init") == 0) {
        if (argc != 2) {
            printf("ERROR: too many agruments given!\n");
            printf("Usage: merk init");
            exit(1);
        }

        if (mkdir(".merk", 0700) == 0) {
            printf("Initialized merk repository\n");
        }

        if (errno == EEXIST) {
            struct stat st;
            if (stat(".merk", &st) == 0 && S_ISDIR(st.st_mode)) {
                printf("This directory is already a merk repository\n");
                return 0;
            }
        }

        mkdir(".merk/files", 0700);
        mkdir(".merk/trees", 0700);
        mkdir(".merk/branches", 0700);
    }

    // Prints out a visual representation of the diff of the files provided
    else if (strcmp(subcmd, "diff") == 0) {
        if (argc != 4) {
            printf("ERROR: too many/little arguments given!\n");
            printf("Usage: merk diff <PATH> <PATH>");
            exit(1);
        }

        File* file1;
        switch (get_path_type(argv[2])) {
            case PT_FILE: file1 = new_file(argv[2]); break;
            case PT_DIR: file1 = NULL; printf("ERROR: first path is a directory and no file!"); break;
            case PT_NOEXIST: file1 = NULL; printf("ERROR: first path does not exist!"); break;
            default: file1 = NULL; printf("ERROR: unknown first path!");
        }
        if (!file1) exit(1);

        File* file2;
        switch (get_path_type(argv[3])) {
            case PT_FILE: file2 = new_file(argv[3]); break;
            case PT_DIR: file2 = NULL; printf("ERROR: second path is a directory and no file!"); break;
            case PT_NOEXIST: file2 = NULL; printf("ERROR: second path does not exist!"); break;
            default: file2 = NULL; printf("ERROR: unknown second path!");
        }
        if (!file2) exit(1);

        ActionList* actions = myers_diff(file1, file2, 0, 0);
        if (!actions) printf("ERROR: something went wrong while taking the diff!");
        else visualize_diff(file1, file2, actions);
    }
    // Gives a list of untracked files in the repo
    else if (strcmp(subcmd, "status") == 0) {
        if (argc != 2) {
            printf("ERROR: too many arguments given!\n");
            printf("Usage: merk status");
            exit(1);
        }

        PathBuffer* files = new_path_buffer();
        char relative[PATH_MAX] = "";
        char* root = find_root(relative);
        if (!root) {
            free_path_buffer(files);
            return 1;
        }

        walk(root, relative, relative, files);

        printf("Untracked files:\n\n");
        for (size_t i = 0; i < files->len; i++) {
            printf("%s\n", files->paths[i]);
        }

        free_path_buffer(files);
        free(root);
        return 0;
    }
    else {
        usage(1);
    }

    return 0;
}