/*
 * This file is part of the public ComputerCraft API - http://www.computercraft.info
 * Copyright Daniel Ratcliffe, 2011-2021. This API may be redistributed unmodified and in full only.
 * For help using the API, and posting your mods, visit the forums at computercraft.info.
 */

package dan200.computercraft.api.lua;

import static dan200.computercraft.api.lua.LuaValues.checkFinite;

import java.nio.ByteBuffer;
import java.util.Map;
import java.util.Optional;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

/**
 * The arguments passed to a function.
 */
public interface IArguments {
    /**
     * Drop a number of arguments. The returned arguments instance will access arguments at position {@code i + count}, rather than {@code i}. However,
     * errors will still use the given argument index.
     *
     * @param count The number of arguments to drop.
     * @return The new {@link IArguments} instance.
     */
    IArguments drop(int count);

    default Object[] getAll() {
        Object[] result = new Object[this.count()];
        for (int i = 0; i < result.length; i++) {
            result[i] = this.get(i);
        }
        return result;
    }

    /**
     * Get the number of arguments passed to this function.
     *
     * @return The number of passed arguments.
     */
    int count();

    /**
     * Get the argument at the specific index. The returned value must obey the following conversion rules:
     *
     * <ul>
     *   <li>Lua values of type "string" will be represented by a {@link String}.</li>
     *   <li>Lua values of type "number" will be represented by a {@link Number}.</li>
     *   <li>Lua values of type "boolean" will be represented by a {@link Boolean}.</li>
     *   <li>Lua values of type "table" will be represented by a {@link Map}.</li>
     *   <li>Lua values of any other type will be represented by a {@code null} value.</li>
     * </ul>
     *
     * @param index The argument number.
     * @return The argument's value, or {@code null} if not present.
     */
    @Nullable
    Object get(int index);

    /**
     * Get an argument as an integer.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not an integer.
     */
    default int getInt(int index) throws LuaException {
        return (int) this.getLong(index);
    }

    /**
     * Get an argument as a long.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not a long.
     */
    default long getLong(int index) throws LuaException {
        Object value = this.get(index);
        if (!(value instanceof Number)) {
            throw LuaValues.badArgumentOf(index, "number", value);
        }
        return LuaValues.checkFiniteNum(index, (Number) value)
                        .longValue();
    }

    /**
     * Get an argument as a finite number (not infinite or NaN).
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not finite.
     */
    default double getFiniteDouble(int index) throws LuaException {
        return checkFinite(index, this.getDouble(index));
    }

    /**
     * Get an argument as a double.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not a number.
     * @see #getFiniteDouble(int) if you require this to be finite (i.e. not infinite or NaN).
     */
    default double getDouble(int index) throws LuaException {
        Object value = this.get(index);
        if (!(value instanceof Number)) {
            throw LuaValues.badArgumentOf(index, "number", value);
        }
        return ((Number) value).doubleValue();
    }

    /**
     * Get an argument as a boolean.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not a boolean.
     */
    default boolean getBoolean(int index) throws LuaException {
        Object value = this.get(index);
        if (!(value instanceof Boolean)) {
            throw LuaValues.badArgumentOf(index, "boolean", value);
        }
        return (Boolean) value;
    }

    /**
     * Get a string argument as a byte array.
     *
     * @param index The argument number.
     * @return The argument's value. This is a <em>read only</em> buffer.
     * @throws LuaException If the value is not a string.
     */
    @Nonnull
    default ByteBuffer getBytes(int index) throws LuaException {
        return LuaValues.encode(this.getString(index));
    }

    /**
     * Get an argument as a string.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not a string.
     */
    @Nonnull
    default String getString(int index) throws LuaException {
        Object value = this.get(index);
        if (!(value instanceof String)) {
            throw LuaValues.badArgumentOf(index, "string", value);
        }
        return (String) value;
    }

    /**
     * Get a string argument as an enum value.
     *
     * @param index The argument number.
     * @param klass The type of enum to parse.
     * @param <T> The type of enum to parse.
     * @return The argument's value.
     * @throws LuaException If the value is not a string or not a valid option for this enum.
     */
    @Nonnull
    default <T extends Enum<T>> T getEnum(int index, Class<T> klass) throws LuaException {
        return LuaValues.checkEnum(index, klass, this.getString(index));
    }

    /**
     * Get an argument as a table.
     *
     * @param index The argument number.
     * @return The argument's value.
     * @throws LuaException If the value is not a table.
     */
    @Nonnull
    default Map<?, ?> getTable(int index) throws LuaException {
        Object value = this.get(index);
        if (!(value instanceof Map)) {
            throw LuaValues.badArgumentOf(index, "table", value);
        }
        return (Map<?, ?>) value;
    }

    /**
     * Get a string argument as a byte array.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present. This is a <em>read only</em> buffer.
     * @throws LuaException If the value is not a string.
     */
    default Optional<ByteBuffer> optBytes(int index) throws LuaException {
        return this.optString(index).map(LuaValues::encode);
    }

    /**
     * Get an argument as a string.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a string.
     */
    default Optional<String> optString(int index) throws LuaException {
        Object value = this.get(index);
        if (value == null) {
            return Optional.empty();
        }
        if (!(value instanceof String)) {
            throw LuaValues.badArgumentOf(index, "string", value);
        }
        return Optional.of((String) value);
    }

    /**
     * Get a string argument as an enum value.
     *
     * @param index The argument number.
     * @param klass The type of enum to parse.
     * @param <T> The type of enum to parse.
     * @return The argument's value.
     * @throws LuaException If the value is not a string or not a valid option for this enum.
     */
    @Nonnull
    default <T extends Enum<T>> Optional<T> optEnum(int index, Class<T> klass) throws LuaException {
        Optional<String> str = this.optString(index);
        return str.isPresent() ? Optional.of(LuaValues.checkEnum(index, klass, str.get())) : Optional.empty();
    }

    /**
     * Get an argument as a double.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a number.
     */
    default double optDouble(int index, double def) throws LuaException {
        return this.optDouble(index).orElse(def);
    }

    /**
     * Get an argument as a double.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a number.
     */
    @Nonnull
    default Optional<Double> optDouble(int index) throws LuaException {
        Object value = this.get(index);
        if (value == null) {
            return Optional.empty();
        }
        if (!(value instanceof Number)) {
            throw LuaValues.badArgumentOf(index, "number", value);
        }
        return Optional.of(((Number) value).doubleValue());
    }

    /**
     * Get an argument as an int.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a number.
     */
    default int optInt(int index, int def) throws LuaException {
        return this.optInt(index).orElse(def);
    }

    /**
     * Get an argument as an int.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a number.
     */
    @Nonnull
    default Optional<Integer> optInt(int index) throws LuaException {
        return this.optLong(index).map(Long::intValue);
    }

    /**
     * Get an argument as a long.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a number.
     */
    default Optional<Long> optLong(int index) throws LuaException {
        Object value = this.get(index);
        if (value == null) {
            return Optional.empty();
        }
        if (!(value instanceof Number)) {
            throw LuaValues.badArgumentOf(index, "number", value);
        }
        return Optional.of(LuaValues.checkFiniteNum(index, (Number) value)
                                    .longValue());
    }

    /**
     * Get an argument as a long.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a number.
     */
    default long optLong(int index, long def) throws LuaException {
        return this.optLong(index).orElse(def);
    }

    /**
     * Get an argument as a finite number (not infinite or NaN).
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not finite.
     */
    default double optFiniteDouble(int index, double def) throws LuaException {
        return this.optFiniteDouble(index).orElse(def);
    }

    /**
     * Get an argument as a finite number (not infinite or NaN).
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not finite.
     */
    default Optional<Double> optFiniteDouble(int index) throws LuaException {
        Optional<Double> value = this.optDouble(index);
        if (value.isPresent()) {
            LuaValues.checkFiniteNum(index, value.get());
        }
        return value;
    }

    /**
     * Get an argument as a boolean.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a boolean.
     */
    default boolean optBoolean(int index, boolean def) throws LuaException {
        return this.optBoolean(index).orElse(def);
    }

    /**
     * Get an argument as a boolean.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a boolean.
     */
    default Optional<Boolean> optBoolean(int index) throws LuaException {
        Object value = this.get(index);
        if (value == null) {
            return Optional.empty();
        }
        if (!(value instanceof Boolean)) {
            throw LuaValues.badArgumentOf(index, "boolean", value);
        }
        return Optional.of((Boolean) value);
    }

    /**
     * Get an argument as a string.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a string.
     */
    default String optString(int index, String def) throws LuaException {
        return this.optString(index).orElse(def);
    }

    /**
     * Get an argument as a table.
     *
     * @param index The argument number.
     * @param def The default value, if this argument is not given.
     * @return The argument's value, or {@code def} if none was provided.
     * @throws LuaException If the value is not a table.
     */
    default Map<?, ?> optTable(int index, Map<Object, Object> def) throws LuaException {
        return this.optTable(index).orElse(def);
    }

    /**
     * Get an argument as a table.
     *
     * @param index The argument number.
     * @return The argument's value, or {@link Optional#empty()} if not present.
     * @throws LuaException If the value is not a table.
     */
    default Optional<Map<?, ?>> optTable(int index) throws LuaException {
        Object value = this.get(index);
        if (value == null) {
            return Optional.empty();
        }
        if (!(value instanceof Map)) {
            throw LuaValues.badArgumentOf(index, "map", value);
        }
        return Optional.of((Map<?, ?>) value);
    }
}