package com.bib.essensbestellungsverwaltung;

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.ArrayList;
import java.util.Base64;
import java.util.List;

/**
 * A collection of functions loosely related to account management
 * Acts as an abstraction layer to the database
 * 
 * @author Malte Schulze Hobeling
 */
public class AccountMgr {

    static User currentUser = null;

    /**
     * creates a user with createUser(...) and adds its id to the 'worker' table
     * 
     * @param worker the worker to be created
     * @return userid or -1
     * @author Malte Schulze Hobeling
     */
    protected static long createWorker(Worker worker) {
        long id = createUser(worker);
        String sId = String.valueOf(id);
        Database.insert("worker", new String[] { "userid" }, new String[] { sId });
        return id;
    }

    /**
     * creates a user with createUser(...) and adds its id to the 'parent' table
     * 
     * @param parent the parent to be created
     * @return userid or -1
     * @author Malte Schulze Hobeling
     */
    protected static long createParent(Parent parent) {
        long id = createUser(parent);
        String sId = String.valueOf(id);
        Database.insert("parent", new String[] { "userid" }, new String[] { sId });
        return id;
    }

    /**
     * adds a user to the database
     * 
     * @param user the user to be created
     * @return userid or -1
     * @author Malte Schulze Hobeling
     */
    protected static long createUser(User user) {
        String[] userH = { "name", "firstname", "addressid", "password", "email" };
        String name = user.getName();
        String firstname = user.getFirstname();
        String pw = hashAndSalt(user.getPassword(), getSalt());
        String email = user.getEmail();
        long addressId = user.getAddress().getId();
        if (addressId < 1) {
            addressId = createAddress(user.getAddress());
        }
        String[] userD = { name, firstname, String.valueOf(addressId), pw, email };
        return Database.insert("user", userH, userD);
    }

    /**
     * adds an address to the database
     * 
     * @param address the address to be created
     * @return id or -1
     * @author Malte Schulze Hobeling
     */
    protected static long createAddress(Address address) {
        String[] addressH = { "street", "number", "plz", "city" };
        String[] addressD = { address.getStreet(), address.getNumber(), address.getPlz(), address.getCity() };
        return Database.insert("address", addressH, addressD);
    }

    /**
     * adds a child and allergies to the database
     * 
     * @param child the child to be created
     * @return id of child or -1
     * @author Malte Schulze Hobeling
     */
    protected static long createChild(Child child) {
        String[] childH = { "name", "firstname", "addressid" };
        String[] childD = { child.getName(), child.getFirstname(), String.valueOf(child.getAddress().getId()) };
        long id = Database.insert("child", childH, childD);
        String[] child_allergyH = { "childid", "allergyid", "severityid" };
        for (AllergySeverity allergy : child.getAllergies()) {
            String sId = String.valueOf(id);
            String sAllergyId = String.valueOf(allergy.getAllergy().getId());
            String sSeverityId = String.valueOf(allergy.getSeverityId());
            String[] child_allergyD = { sId, sAllergyId, sSeverityId };
            Database.insert("child_allergy", child_allergyH, child_allergyD);
        }
        return id;
    }

    /**
     * update Child
     *
     * @param child the child to be updated
     * @return id of child
     * @author Johannes Kantz
     */
    protected static long updateChild(Child child) {
        String[] childH = { "id", "name", "firstname", "addressid" };
        String[] childD = { String.valueOf(child.getId()), child.getName(), child.getFirstname(),
                String.valueOf(child.getAddress().getId()) };
        long updates = Database.update("child", childH, childD);
        String[] child_allergyH = { "childid", "allergyid", "severityid" };
        Database.select("child_allergy", new String[] { "childid" }, new String[] { String.valueOf(child.getId()) })
                .stream().forEach(row -> {
                    String allergyId = row.split(":")[0];
                    Database.delete("child_allergy", Integer.parseInt(allergyId));
                });
        for (AllergySeverity allergy : child.getAllergies()) {
            String sId = String.valueOf(child.getId());
            String sAllergyId = String.valueOf(allergy.getAllergy().getId());
            String sSeverityId = String.valueOf(allergy.getSeverityId());
            String[] child_allergyD = { sId, sAllergyId, sSeverityId };
            Database.insert("child_allergy", child_allergyH, child_allergyD);
        }
        return updates;
    }

    /**
     * delete Child
     * 
     * @author Johannes Kantz
     */
    protected static void deleteChildWithId(long id) {
        Database.delete("child", id);
        Database.select("child_allergy", new String[] { "childid" }, new String[] { String.valueOf(id) }).stream()
                .forEach(row -> {
                    String allergyId = row.split(":")[0];
                    Database.delete("child_allergy", Integer.parseInt(allergyId));
                });
    }

    /**
     * returns a User(Worker | Parent) for a given id or null if no unique id was
     * found
     * 
     * @param id id of the User
     * @return User(Worker | Parent) or null
     * @author Malte Schulze Hobeling
     */
    protected static User getUserById(long id) {
        List<String> entry = Database.getEntryById("user", id);
        if (entry.size() != 1) {
            return null;
        }
        String[] parts = entry.get(0).split(":");
        Address address = getAddressById(id);
        if (isWorker(String.valueOf(id))) {
            return new Worker(id, parts[1], parts[2], parts[4], parts[5], address);
        } else {
            String[] parent_childH = { "parentuserid" };
            String[] parent_childD = { String.valueOf(id) };
            List<Child> children = new ArrayList<>();
            List<String> parent_childEntries = Database.select("parent_child", parent_childH, parent_childD);
            for (String parent_childEntry : parent_childEntries) {
                String[] parent_childParts = parent_childEntry.split(":");
                children.add(getChildById(Long.parseLong(parent_childParts[2])));
            }
            return new Parent(id, parts[1], parts[2], parts[4], parts[5], address, children);
        }
    }

    /**
     * returns a Child for a given id or null if no unique id was found
     * 
     * @param id id of child
     * @return Child or null
     * @author Malte Schulze Hobeling
     */
    protected static Child getChildById(long id) {
        List<String> entry = Database.getEntryById("child", id);
        if (entry.size() != 1) {
            return null;
        }
        String[] parts = entry.get(0).split(":");
        String[] child_allergyH = { "childid" };
        String[] child_allergyD = { String.valueOf(id) };
        List<String> entriesAllergy = Database.select("child_allergy", child_allergyH, child_allergyD);
        List<AllergySeverity> allergySeverities = new ArrayList<>();
        for (String entryAllergy : entriesAllergy) {
            String[] allergyParts = entryAllergy.split(":");
            List<String> severity = Database.getEntryById("severity", Long.parseLong(allergyParts[3]));
            String sSeverity = severity.get(0).split(":")[1];
            long lSeverity = Long.parseLong(severity.get(0).split(":")[0]);
            allergySeverities.add(
                    new AllergySeverity(FoodMgr.getAllergyById(Long.parseLong(allergyParts[2])), lSeverity, sSeverity));
        }
        return new Child(id, parts[1], parts[2], getAddressById(Long.parseLong(parts[3])), allergySeverities);
    }

    /**
     * returns all Children
     * 
     * @return {List<Child} List with Childen or empty List
     * @author Johannes Kantz
     */
    protected static List<Child> getAllChildren() {
        List<String> entry = Database.getTable("child");
        if (entry.size() < 1) {
            return new ArrayList<>();
        }
        List<Child> children = new ArrayList<>();
        for (String s : entry) {
            String[] parts = s.split(":");
            String[] child_allergyH = { "childid" };
            String[] child_allergyD = { String.valueOf(parts[0]) };
            List<String> entriesAllergy = Database.select("child_allergy", child_allergyH, child_allergyD);
            List<AllergySeverity> allergySeverities = new ArrayList<>();
            for (String entryAllergy : entriesAllergy) {
                String[] allergyParts = entryAllergy.split(":");
                List<String> severity = Database.getEntryById("severity", Long.parseLong(allergyParts[3]));
                String sSeverity = severity.get(0).split(":")[1];
                long lSeverity = Long.parseLong(severity.get(0).split(":")[0]);
                allergySeverities.add(new AllergySeverity(FoodMgr.getAllergyById(Long.parseLong(allergyParts[2])),
                        lSeverity, sSeverity));
            }
            children.add(new Child(Long.parseLong(parts[0]), parts[1], parts[2],
                    getAddressById(Long.parseLong(parts[3])), allergySeverities));
        }
        return children;
    }

    /**
     * returns all Children from parent
     * @param id parentid
     * @return {List<Child} List with Childen or empty List
     * @author Johannes Kantz
     */
    protected static List<Child> getAllChildrenFromParentWithId(long id) {
        List<String> entry = Database.select("parent_child", new String[] { "parentuserid" },
                new String[] { String.valueOf(id) });
        if (entry.size() < 1) {
            return new ArrayList<>();
        }
        List<String> childIds = new ArrayList<>();
        for (String s : entry) {
            String[] parts = s.split(":");
            childIds.add(parts[2]);
        }
        List<Child> children = new ArrayList<>();
        for (String s : childIds) {
            List<String> child = Database.getEntryById("child", Long.parseLong(s));
            String[] parts = child.get(0).split(":");
            String[] child_allergyH = { "childid" };
            String[] child_allergyD = { String.valueOf(parts[0]) };
            List<String> entriesAllergy = Database.select("child_allergy", child_allergyH, child_allergyD);
            List<AllergySeverity> allergySeverities = new ArrayList<>();
            for (String entryAllergy : entriesAllergy) {
                String[] allergyParts = entryAllergy.split(":");
                List<String> severity = Database.getEntryById("severity", Long.parseLong(allergyParts[3]));
                String sSeverity = severity.get(0).split(":")[1];
                long lSeverity = Long.parseLong(severity.get(0).split(":")[0]);
                allergySeverities.add(new AllergySeverity(FoodMgr.getAllergyById(Long.parseLong(allergyParts[2])),
                        lSeverity, sSeverity));
            }
            children.add(new Child(Long.parseLong(parts[0]), parts[1], parts[2],
                    getAddressById(Long.parseLong(parts[3])), allergySeverities));
        }
        return children;
    }

    /**
     * returns an Address for a given id or null if no unique id was found
     * 
     * @param id id of the address
     * @return Address or null
     * @author Malte Schulze Hobeling
     */
    protected static Address getAddressById(long id) {
        List<String> entry = Database.getEntryById("address", id);
        if (entry.size() != 1) {
            return null;
        }
        String[] parts = entry.get(0).split(":");
        return new Address(Long.parseLong(parts[0]), parts[1], parts[2], parts[3], parts[4]);
    }

    /**
     * creates entries in the database to match parent to child
     * 
     * @param parentId id of parent
     * @param childId  id of child
     * @return id of parent_child or -1
     * @author Malte Schulze Hobeling
     */
    protected static long matchParentChild(String parentId, String childId) {
        String[] parent_childH = { "parentuserid", "childid" };
        String[] parent_childD = { parentId, childId };
        return Database.insert("parent_child", parent_childH, parent_childD);
    }

    /**
     * a simple login to check if a given email matches a password
     * 
     * @param email email
     * @param pw    password
     * @return id or -1
     * @author Malte Schulze Hobeling
     */
    protected static long login(String email, String pw) {
        String[] pwH = { "email" };
        String[] pwD = { email };
        List<String> foundEmail = Database.select("user", pwH, pwD);
        String salt;
        if (foundEmail.size() == 1) {
            String[] userParts = foundEmail.get(0).split(":");
            String[] pwParts = userParts[4].split("\\.");
            salt = pwParts[1];
        } else {
            // no unique user found; still calculating a hash for security reasons
            salt = getSalt();
        }
        String[] userH = { "email", "password" };
        String[] userD = { email, hashAndSalt(pw, salt) };
        return Database.getSingleId("user", userH, userD);
    }

    /**
     * checks if id is in worker table
     * 
     * @param id userid
     * @return true if id is in worker table
     * @author Malte Schulze Hobeling
     */
    protected static boolean isWorker(String id) {
        String[] workerH = { "userid" };
        String[] workerD = { id };
        long workerId = Database.getSingleId("worker", workerH, workerD);
        return workerId > 0;
    }

    /**
     * checks if id is in parent table
     * 
     * @param id userid
     * @return true if id is in parent table
     * @author Malte Schulze Hobeling
     */
    protected static boolean isParent(String id) {
        String[] parentH = { "userid" };
        String[] parentD = { id };
        long parentId = Database.getSingleId("parent", parentH, parentD);
        return parentId > 0;
    }

    /**
     * returns a hashed and salted password
     * 
     * @param pw the password to hash
     * @return hashed and salted password
     * @author Malte Schulze Hobeling
     */
    private static String hashAndSalt(String pw, String salt) {
        Base64.Decoder dec = Base64.getDecoder();
        byte[] bySalt = dec.decode(salt);
        KeySpec spec = new PBEKeySpec(pw.toCharArray(), bySalt, 310001, 256);
        String hashedPw;
        try {
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
            byte[] hash = factory.generateSecret(spec).getEncoded();
            Base64.Encoder enc = Base64.getEncoder();
            hashedPw = enc.encodeToString(hash);
        } catch (InvalidKeySpecException | NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
        hashedPw += "." + salt;
        return hashedPw;
    }

    /**
     * generates a secure random salt, Base64 encoded
     * 
     * @return String Base64 encoded
     * @author Malte Schulze Hobeling
     */
    private static String getSalt() {
        SecureRandom sec = new SecureRandom();
        byte[] salt = new byte[16];
        sec.nextBytes(salt);
        Base64.Encoder enc = Base64.getEncoder();
        return enc.encodeToString(salt);
    }

    /**
     * gives the invoice for one month and one child
     * 
     * @param date    YYYY-MM the month
     * @param childId id of child
     * @return the invoice as a List
     * @author Malte Schulze Hobeling
     */
    protected static List<String> getInvoice(String date, String childId) {
        List<String> invoice = new ArrayList<>();
        List<String> child = Database.getEntryById("child", Long.parseLong(childId));
        if (child.size() != 1) {
            return invoice;
        }
        invoice.add("Monatsabrechnung " + date);
        String[] childParts = child.get(0).split(":");
        invoice.add(childParts[1] + ", " + childParts[2]);
        String[] food_planH = { "date" };
        String[] food_planD = { date + "%" };
        List<String> food_plan = Database.select("food_plan", food_planH, food_planD);
        for (String day : food_plan) {
            String[] food_planParts = day.split(":");
            String[] food_selectionH = { "childid", "food_planid" };
            String[] food_selectionD = { childId, food_planParts[0] };
            List<String> food_selection = Database.select("food_selection", food_selectionH, food_selectionD);
            for (String food_select : food_selection) {
                String[] food_selectParts = food_select.split(":");
                List<String> food = Database.getEntryById("food", Long.parseLong(food_selectParts[3]));
                String[] foodParts = food.get(0).split(":");
                String line = food_planParts[1] + ": " + foodParts[1];
                invoice.add(line);
            }
        }
        double price = getPrice();
        invoice.add("Total: " + (invoice.size() - 2) + " X " + price + "€ = " + ((invoice.size() - 2) * price) + "€");
        return invoice;
    }

    /**
     * gets the price per meal from the database and converts it to double
     * 
     * @return double price
     * @author Malte Schulze Hobeling
     */
    protected static double getPrice() {
        List<String> priceEntry = Database.getEntryById("price", 1);
        return Double.parseDouble(priceEntry.get(0).split(":")[1]) / 100.0;
    }

    /**
     * converts the price per meal to integer and updates it in the database
     * 
     * @param price double
     * @author Malte Schulze Hobeling
     */
    protected static void setPrice(double price) {
        String[] priceH = { "id", "price" };
        String[] priceD = { "1", String.valueOf((int) (price * 100)) };
        Database.update("price", priceH, priceD);
    }
}