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

#define YAML_IMPLEMENTATION
#include "../include/cyaml.h"

// Define a simple User struct.
typedef struct {
    int id;
    char name[100];
    char email[100];
} User;

#define MAX_USERS 100

User users[MAX_USERS];
size_t user_count = 0;

// Display the list of users.
void list_users(void) {
    printf("\n-- User Database --\n");
    if (user_count == 0) {
        printf("No users found.\n");
        return;
    }
    for (size_t i = 0; i < user_count; i++) {
        printf("ID %d: %s, %s\n", users[i].id, users[i].name, users[i].email);
    }
}

// Save the in-memory user database to a YAML file.
// The output YAML file will have a mapping with the key "users"
// which contains a sequence of mappings (each representing a user).
int save_to_file(const char *filename) {
    // Create a new document with a mapping as root.
    YAMLDoc *doc = (YAMLDoc*)malloc(sizeof(YAMLDoc));
    if (!doc) return -1;
    doc->root = yaml_new_map();
    if (!doc->root) {
        free(doc);
        return -1;
    }

    // Create a sequence to hold all user mappings.
    YAMLNode *userSeq = yaml_new_seq();
    if (!userSeq) {
        yaml_doc_destroy(doc);
        return -1;
    }

    // For each user, create a mapping and add it to the sequence.
    for (size_t i = 0; i < user_count; i++) {
        YAMLNode *userMap = yaml_new_map();
        char idStr[20];
        snprintf(idStr, sizeof(idStr), "%d", users[i].id);
        yaml_map_set(userMap, "id", yaml_new_str(idStr));
        yaml_map_set(userMap, "name", yaml_new_str(users[i].name));
        yaml_map_set(userMap, "email", yaml_new_str(users[i].email));
        yaml_seq_append(userSeq, userMap);
    }
    yaml_map_set(doc->root, "users", userSeq);

    // Create an emitter and write the document to the file.
    YAMLEmitter *emitter = yaml_emitter_create();
    if (!emitter) {
        yaml_doc_destroy(doc);
        return -1;
    }
    if (yaml_emit(emitter, doc) != 0) {
        yaml_emitter_destroy(emitter);
        yaml_doc_destroy(doc);
        return -1;
    }
    int ret = yaml_emit_to_file(emitter, filename);

    // Clean up.
    yaml_emitter_destroy(emitter);
    yaml_doc_destroy(doc);
    return ret;
}

// Add a new user via CLI.
void add_user(void) {
    if (user_count >= MAX_USERS) {
        printf("User database is full.\n");
        return;
    }
    User newUser;
    newUser.id = user_count + 1; // Simple sequential id assignment.

    printf("Enter user name: ");
    if (!fgets(newUser.name, sizeof(newUser.name), stdin)) {
        printf("Error reading name.\n");
        return;
    }
    newUser.name[strcspn(newUser.name, "\n")] = '\0'; // Remove newline.

    printf("Enter user email: ");
    if (!fgets(newUser.email, sizeof(newUser.email), stdin)) {
        printf("Error reading email.\n");
        return;
    }
    newUser.email[strcspn(newUser.email, "\n")] = '\0';

    users[user_count++] = newUser;
    printf("User added successfully.\n");
}

// Edit an existing user via CLI.
void edit_user(void) {
    list_users();
    printf("Enter the user ID to edit: ");
    int id;
    if (scanf("%d", &id) != 1) {
        printf("Invalid input.\n");
        while(getchar() != '\n'); // Flush input buffer.
        return;
    }
    while(getchar() != '\n'); // Consume newline.

    int found = 0;
    for (size_t i = 0; i < user_count; i++) {
        if (users[i].id == id) {
            found = 1;
            printf("Editing user (ID %d): %s, %s\n", users[i].id, users[i].name, users[i].email);
            printf("Enter new name (leave empty to keep unchanged): ");
            char newName[100];
            if (fgets(newName, sizeof(newName), stdin)) {
                newName[strcspn(newName, "\n")] = '\0';
                if (strlen(newName) > 0)
                    strncpy(users[i].name, newName, sizeof(users[i].name));
            }
            printf("Enter new email (leave empty to keep unchanged): ");
            char newEmail[100];
            if (fgets(newEmail, sizeof(newEmail), stdin)) {
                newEmail[strcspn(newEmail, "\n")] = '\0';
                if (strlen(newEmail) > 0)
                    strncpy(users[i].email, newEmail, sizeof(users[i].email));
            }
            printf("User updated successfully.\n");
            break;
        }
    }
    if (!found)
        printf("User with ID %d not found.\n", id);
}

int main(void) {
    int running = 1;
    while (running) {
        printf("\n--- User Database CLI ---\n");
        printf("1. List users\n");
        printf("2. Add user\n");
        printf("3. Edit user\n");
        printf("4. Save database to file\n");
        printf("5. Exit\n");
        printf("Enter choice: ");

        int choice;
        if (scanf("%d", &choice) != 1) {
            printf("Invalid input. Please enter a number.\n");
            while(getchar() != '\n'); // Clear the invalid input.
            continue;
        }
        while(getchar() != '\n'); // Consume newline.

        switch (choice) {
            case 1:
                list_users();
                break;
            case 2:
                add_user();
                break;
            case 3:
                edit_user();
                break;
            case 4: {
                char filename[256];
                printf("Enter filename to save the database: ");
                if (fgets(filename, sizeof(filename), stdin)) {
                    filename[strcspn(filename, "\n")] = '\0';
                    if (save_to_file(filename) == 0)
                        printf("Database saved successfully to '%s'.\n", filename);
                    else
                        printf("Error saving database to '%s'.\n", filename);
                }
                break;
            }
            case 5:
                running = 0;
                break;
            default:
                printf("Invalid choice. Please try again.\n");
        }
    }
    return 0;
}