/* toradora.c - A terminal based todo list */
/* Using a sqlite database at ~/.toradora.db we will keep track of all the
 * entries */

/** FEATURES **/
/*
 * 1. Able to add tasks. (toradora -a "The task I want to add")
 * 2. Able to complete those tasks. (toradora -c 1 )
 * 3. Able to edit those tasks. (toradora -e 1 "The previous task edited")
 * 4. Able to manifest those tasks. (toradora)
 * ===============================
 * >>> Today's Task <<<
 * 1. "task one"
 * 2. "task two"
 *
 * >>> Backlogs <<<
 * 3. "task three"
 * ===============================
 * 5. Able to manifest all the tasks in database. (toradora -z)
 *
 */

#include <sqlite3.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define VERSION "0.1.0"

#define MAX_PATH_LENGTH 4096

static void
manifest_usage()
{
    printf("toradora - a terminal based todo list\n\n");
    printf("Usage:\n");
    printf("  toradora                        Show today's tasks and backlog\n");
    printf("  toradora -z                     Show all tasks ever recorded\n");
    printf("  toradora -a \"task\"              Add a new task\n");
    printf("  toradora -c <id>                Mark task <id> as complete\n");
    printf("  toradora -e <id> \"new task\"     Edit task <id>\n\n");
    printf("Examples:\n");
    printf("  toradora -a \"write usage function\"\n");
    printf("  toradora -c 3\n");
    printf("  toradora -e 3 \"write usage function (done)\"\n");
}

static int
callback_manifest(void *data, int argc, char **argv, char **az_col_name)
{
	/* fprintf(stderr, "%s: ", (const char *)data); */
    printf("%s. %s\n", argv[0], argv[1]);
    printf("\n");
    return 0;
}


static void
manifest_active_tasks(sqlite3 *DB)
{
    int query_status;
    char *message_error_1;
    char *message_error_2;
    printf("----------------------------------------------\n");
	printf(">>> Today's Task <<<\n");
	char *manifest_query_1 = "SELECT ID, TASK FROM tasks WHERE STATUS = 0 "
        "AND created_at = CURRENT_DATE;";
    query_status = sqlite3_exec(DB, manifest_query_1, callback_manifest, "Manifest callback", &message_error_1);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("%s\n", message_error_1);
        printf("[Help]: Check database sanity\n");
        return;
    }

    printf(">>> Backlog <<<\n");
	char *manifest_query_2 = "SELECT ID, TASK FROM tasks WHERE STATUS = 0 "
        "AND created_at != CURRENT_DATE;";
    query_status = sqlite3_exec(DB, manifest_query_2, callback_manifest, "Manifest callback", &message_error_2);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("%s\n", message_error_2);
        printf("[Help]: Check database sanity\n");
        return;
    }
    printf("----------------------------------------------\n");
}

static void
manifest_all_tasks(sqlite3 *DB)
{
	int query_status;
	char *message_error;
    printf("----------------------------------------------\n");
    printf(">>> All tasks ever recorded\n");
    char *manifest_query = "SELECT ID, TASK FROM tasks;";
    query_status = sqlite3_exec(DB, manifest_query, callback_manifest, "Manifest callback", &message_error);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("%s\n", message_error);
        printf("[Help]: Check database sanity\n");
        return;
    }
    printf("----------------------------------------------\n");
}

static void
toradora_add_task(sqlite3 *DB, const char *todo)
{
	sqlite3_stmt *stmt = NULL;
	int query_status;

	const char *add_query = "INSERT INTO TASKS (task) VALUES (?);";

    query_status = sqlite3_prepare_v2(DB, add_query, -1, &stmt, NULL);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }

    sqlite3_bind_text(stmt, 1, todo, -1, SQLITE_STATIC);
    query_status = sqlite3_step(stmt);
    if (query_status != SQLITE_DONE) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }
    error:
    sqlite3_finalize(stmt);

}

static void
toradora_complete_task(sqlite3 *DB, const char *id)
{
	sqlite3_stmt *stmt = NULL;
	int query_status;
	int curr;
    char *end_ptr;
    int row_affected;
	const char *complete_query = "UPDATE TASKS SET status = 1 WHERE id = ?;";

    query_status = sqlite3_prepare_v2(DB, complete_query, -1, &stmt, NULL);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }
    curr = (int)strtol(id, &end_ptr, 10);
    if (*end_ptr != '\0') {
	    printf("[Error]: Invalid argument");
        manifest_usage();
        goto error;
    }
    sqlite3_bind_int(stmt, 1, curr);
    query_status = sqlite3_step(stmt);
    if (query_status != SQLITE_DONE) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }
    row_affected = sqlite3_changes(DB);
    if (row_affected == 0) {
	    printf("[Info]: No rows were affected\n");
        printf("[Help]: Did you entered valid task id?\n");
    }
    error:
    sqlite3_finalize(stmt);
}


static void
toradora_edit_task(sqlite3 *DB, const char *id, const char *new_task)
{
	sqlite3_stmt *stmt = NULL;
	int query_status;
	int curr;
    char *end_ptr;
    int row_affected;
	const char *complete_query = "UPDATE TASKS SET task = ? WHERE id = ?;";

    query_status = sqlite3_prepare_v2(DB, complete_query, -1, &stmt, NULL);
    if (query_status != SQLITE_OK) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }
    curr = (int)strtol(id, &end_ptr, 10);
    if (*end_ptr != '\0') {
	    printf("[Error]: Invalid argument");
        manifest_usage();
        goto error;
    }
    sqlite3_bind_text(stmt, 1, new_task, -1, SQLITE_STATIC);
    sqlite3_bind_int(stmt, 2, curr);
    query_status = sqlite3_step(stmt);
    if (query_status != SQLITE_DONE) {
        printf("[Error]: Unexpected error during execution of query\n");
        printf("[Help]: Check database sanity\n");
        goto error;
    }
    row_affected = sqlite3_changes(DB);
    if (row_affected == 0) {
	    printf("[Info]: No rows were affected\n");
        printf("[Help]: Did you entered valid task id?\n");
    }
    error:
    sqlite3_finalize(stmt);
}

int
main(int argc, char *argv[])
{
    char *home_path = getenv("HOME");
    char *file_path = "/.toradora.db";
    char database_path[MAX_PATH_LENGTH];
	sqlite3 *DB;
	int db_exit = 0;
	int tab_exit = 0;
    char *message_error;

    if (home_path == NULL) {
        printf("[Error]: HOME environment variable not set.\n");
        return -1;
    }
    snprintf(database_path, sizeof(database_path), "%s%s", home_path, file_path);


	db_exit = sqlite3_open(database_path, &DB);
	if (db_exit) {
		printf("[Error]: Database corrupted\n");
        printf("[Help]: Delete database file and rerun the application");
        return -1;
	}

    char *create_table = "CREATE TABLE IF NOT EXISTS tasks ("
        "id INTEGER PRIMARY KEY NOT NULL,"
        "task TEXT NOT NULL,"
        "status INTEGER NOT NULL DEFAULT 0,"
        "created_at TEXT NOT NULL DEFAULT CURRENT_DATE"
        ");";

    tab_exit = sqlite3_exec(DB, create_table, NULL, 0, &message_error);

    if (tab_exit != SQLITE_OK) {
	    printf("[Error]: Table creation failed\n");
        printf("%s\n", message_error);
        return -1;
    }

	switch (argc) {
	case 1:
		manifest_active_tasks(DB);
		break;
	case 2:
		if (0 == strcmp(argv[1], "-z")) {
            manifest_all_tasks(DB);
		} else {
            manifest_usage();
            return 1;
		}
        break;
	case 3:
		if (0 == strcmp(argv[1], "-a")) {
            toradora_add_task(DB, argv[2]);
		} else if (0 == strcmp(argv[1], "-c")) {
            toradora_complete_task(DB, argv[2]);
		} else if (0 == strcmp(argv[1], "-h")) {
            manifest_usage();
		} else {
            manifest_usage();
            return 1;
		}
        break;
	case 4:
		if (0 == strcmp(argv[1], "-e")) {
            toradora_edit_task(DB, argv[2], argv[3]);
		} else {
            manifest_usage();
            return 1;
		}
        break;
	default:
        manifest_usage();
        return 1;
	}
    sqlite3_close(DB);
    return 0;
}