use super::command::{
    Help,
    HelpOptions,
    HelpFunction
};
pub use super::{
    Args,
    CommandGroup,
    CommandOptions,
    CommandError,
    HelpBehaviour
};

use utils::Colour;
use std::{
    fmt::Write,
    sync::Arc
};

pub struct CreateHelpCommand(pub HelpOptions, pub HelpFunction);

impl CreateHelpCommand {

    /// Sets a message displaying if input could not be found
    /// but a similar command is available.
    ///
    /// **Note**: `{}` will be substituted with the actual suggested command-name.
    /// Hence no `{}` results in no command-name.
    pub fn suggestion_text(mut self, text: &str) -> Self {
        self.0.suggestion_text = text.to_string();

        self
    }

    /// Sets a message displaying if there is no help available.
    pub fn no_help_available_text(mut self, text: &str) -> Self {
        self.0.no_help_available_text = text.to_string();

        self
    }

    /// Sets a label for usage of a command.
    pub fn usage_label(mut self, text: &str) -> Self {
        self.0.usage_label = text.to_string();

        self
    }

    /// Sets a label for the usage examples of a command.
    pub fn usage_sample_label(mut self, text: &str) -> Self {
        self.0.usage_sample_label = text.to_string();

        self
    }

    /// Sets a label for ungrouped-commands
    pub fn ungrouped_label(mut self, text: &str) -> Self {
        self.0.ungrouped_label = text.to_string();

        self
    }

    /// Sets a label for grouped-commands.
    pub fn grouped_label(mut self, text: &str) -> Self {
        self.0.grouped_label = text.to_string();

        self
    }

    /// Sets a label for aliases.
    pub fn aliases_label(mut self, text: &str) -> Self {
        self.0.aliases_label = text.to_string();

        self
    }

    /// Sets a message displaying if a command is only available
    /// in guilds.
    pub fn guild_only_text(mut self, text: &str) -> Self {
        self.0.guild_only_text = text.to_string();

        self
    }

    /// Sets a message displaying if a command is only available
    /// in direct messages (DMs);
    pub fn dm_only_text(mut self, text: &str) -> Self {
        self.0.dm_only_text = text.to_string();

        self
    }

    /// Sets a message displaying if a command is available in
    /// guilds and DMs.
    pub fn dm_and_guilds_text(mut self, text: &str) -> Self {
        self.0.dm_and_guild_text = text.to_string();

        self
    }

    /// Sets a message displaying if a command is available to use.
    pub fn available_text(mut self, text: &str) -> Self {
        self.0.available_text = text.to_string();

        self
    }

    /// Sets a message that will appear upon failing to find
    /// an individual command.
    /// As in: `{prefix}help {command_name}`, but a command or
    /// alias like `{command_name}` does not exist.
    ///
    /// **Note**: `{}` will be substituted with the actual suggested command-name.
    /// Hence no `{}` results in no command-name.
    pub fn command_not_found_text(mut self, text: &str) -> Self {
        self.0.command_not_found_text = text.to_string();

        self
    }

    /// Sets the message on top of the help-menu, informing the
    /// user how to obtain more information about a single command.
    pub fn individual_command_tip(mut self, text: &str) -> Self {
        self.0.individual_command_tip = text.to_string();

        self
    }

    /// Sets how the group-prefix shall be labeled.
    pub fn group_prefix(mut self, text: &str) -> Self {
        self.0.group_prefix = text.to_string();

        self
    }

    /// Sets how a command requiring roles, that a user is lacking,
    /// shall appear in the help-menu.
    pub fn lacking_role(mut self, behaviour: HelpBehaviour) -> Self {
        self.0.lacking_role = behaviour;

        self
    }

    /// Sets how a command requiring permission, that a user is lacking,
    /// shall be appear in the help-menu.
    pub fn lacking_permissions(mut self, behaviour: HelpBehaviour) -> Self {
        self.0.lacking_permissions = behaviour;

        self
    }

    /// Sets how a command requiring to be sent in either via DM
    /// or a guild should be treated in the help-menu.
    pub fn wrong_channel(mut self, behaviour: HelpBehaviour) -> Self {
        self.0.wrong_channel = behaviour;

        self
    }

    /// Sets the tip (or legend) explaining why some commands are striked,
    /// given text will be used in guilds and direct messages.
    ///
    /// By default this is `Some(String)` and the `String` is empty resulting
    /// in an automated substitution based on your `HelpBehaviour`-settings.
    /// If set to `None`, no tip will be given nor will it be substituted.
    /// If set to a non-empty `Some(String)`, the `String` will be displayed as tip.
    ///
    /// **Note**: [`CreateHelpCommand::striked_commands_tip_in_direct_message`] and
    /// [`CreateHelpCommand::striked_commands_tip_in_guild`] can specifically set this text
    /// for direct messages and guilds.
    ///
    /// [`CreateHelpCommand::striked_commands_tip_in_direct_message`]: #method.striked_commands_tip_in_direct_message
    /// [`CreateHelpCommand::striked_commands_tip_in_guild`]: #method.striked_commands_tip_in_guild
    pub fn striked_commands_tip(mut self, text: Option<String>) -> Self {
        self.0.striked_commands_tip_in_dm = text.clone();
        self.0.striked_commands_tip_in_guild = text;

        self
    }

    /// Sets the tip (or legend) explaining why some commands are striked,
    /// given text will be used in guilds.
    ///
    /// By default this is `Some(String)` and the `String` is empty resulting
    /// in an automated substitution based on your `HelpBehaviour`-settings.
    /// If set to `None`, no tip will be given nor will it be substituted.
    /// If set to a non-empty `Some(String)`, the `String` will be displayed as tip.
    pub fn striked_commands_tip_in_guild(mut self, text: Option<String>) -> Self {
        self.0.striked_commands_tip_in_guild = text;

        self
    }

    /// Sets the tip (or legend) explaining why some commands are striked,
    /// given text will be used in direct messages.
    ///
    /// By default this is `Some(String)` and the `String` is empty resulting
    /// in an automated substitution based on your `HelpBehaviour`-settings.
    /// If set to `None`, no tip will be given nor will it be substituted.
    /// If set to a non-empty `Some(String)`, the `String` will be displayed as tip.
    pub fn striked_commands_tip_in_direct_message(mut self, text: Option<String>) -> Self {
        self.0.striked_commands_tip_in_dm = text;

        self
    }

    /// Sets the colour for the embed if no error occurred.
    pub fn embed_success_colour(mut self, colour: Colour) -> Self {
        self.0.embed_success_colour = colour;

        self
    }

    /// Sets the colour for the embed if an error occurred.
    pub fn embed_error_colour(mut self, colour: Colour) -> Self {
        self.0.embed_error_colour = colour;

        self
    }

    /// Sets the maximum Levenshtein-distance to find similar commands.
    pub fn max_levenshtein_distance(mut self, distance: usize) -> Self {
        self.0.max_levenshtein_distance = distance;

        self
    }

    fn produce_strike_text(&self, dm_or_guild: &str) -> Option<String> {
        let mut strike_text = String::from("~~`Strikethrough commands`~~ are unavailable because they");
        let mut is_any_option_strike = false;

        let mut concat_with_comma = if self.0.lacking_permissions == HelpBehaviour::Strike {
            is_any_option_strike = true;
            let _ = write!(strike_text, " require permissions");

            true
        } else {
            false
        };

        if self.0.lacking_role == HelpBehaviour::Strike {
            is_any_option_strike = true;

            if concat_with_comma {
                let _ = write!(strike_text, ", require a specific role");
            } else {
                let _ = write!(strike_text, " require a specific role");
                concat_with_comma = true;
            }
        }

        if self.0.wrong_channel == HelpBehaviour::Strike {
            is_any_option_strike = true;

            if concat_with_comma {
                strike_text.push_str(&format!(", or are limited to {}", dm_or_guild));
            } else {
                strike_text.push_str(&format!(" are limited to {}", dm_or_guild));
            }
        }
        let _ = write!(strike_text, ".");

        if is_any_option_strike {
            Some(strike_text)
        } else {
            None
        }
    }

    /// Finishes the creation of a help-command, returning `Help`.
    /// If `Some(String)` was set as `striked_commands_tip` and the `String` is empty,
    /// the creator will substitute content based on the `HelpBehaviour`-settings.
    pub(crate) fn finish(mut self) -> Arc<Help> {
        if self.0.striked_commands_tip_in_dm == Some(String::new()) {
            self.0.striked_commands_tip_in_dm = self.produce_strike_text("direct messages");
        }

        if self.0.striked_commands_tip_in_guild == Some(String::new()) {
            self.0.striked_commands_tip_in_guild = self.produce_strike_text("guild messages");
        }

        let CreateHelpCommand(options, function) = self;

        Arc::new(Help(function, Arc::new(options)))
    }
}