use anyhow::Result;
use clap::Parser;
#[cfg(feature = "imap")]
use email::message::{get::imap::GetMessagesImap, peek::imap::PeekMessagesImap};
#[cfg(feature = "maildir")]
use email::{flag::add::maildir::AddFlagsMaildir, message::peek::maildir::PeekMessagesMaildir};
use log::info;
use mml::message::FilterParts;

#[cfg(feature = "sync")]
use crate::cache::arg::disable::CacheDisableFlag;
use crate::{
    account::arg::name::AccountNameFlag,
    backend::{Backend, BackendKind},
    config::TomlConfig,
    envelope::arg::ids::EnvelopeIdsArgs,
    folder::arg::name::FolderNameOptionalFlag,
    printer::Printer,
};

/// Read a message.
///
/// This command allows you to read a message. When reading a message,
/// the "seen" flag is automatically applied to the corresponding
/// envelope. To prevent this behaviour, use the --preview flag.
#[derive(Debug, Parser)]
pub struct MessageReadCommand {
    #[command(flatten)]
    pub folder: FolderNameOptionalFlag,

    #[command(flatten)]
    pub envelopes: EnvelopeIdsArgs,

    /// Read the message without applying the "seen" flag to its
    /// corresponding envelope.
    #[arg(long, short)]
    pub preview: bool,

    /// Read the raw version of the given message.
    ///
    /// The raw message represents the headers and the body as it is
    /// on the backend, unedited: not decoded nor decrypted. This is
    /// useful for debugging faulty messages, but also for
    /// saving/sending/transfering messages.
    #[arg(long, short)]
    #[arg(conflicts_with = "no_headers")]
    #[arg(conflicts_with = "headers")]
    pub raw: bool,

    /// Read only body of text/html parts.
    ///
    /// This argument is useful when you need to read the HTML version
    /// of a message. Combined with --no-headers, you can write it to
    /// a .html file and open it with your favourite browser.
    #[arg(long)]
    #[arg(conflicts_with = "raw")]
    pub html: bool,

    /// Read only the body of the message.
    ///
    /// All headers will be removed from the message.
    #[arg(long)]
    #[arg(conflicts_with = "raw")]
    #[arg(conflicts_with = "headers")]
    pub no_headers: bool,

    /// List of headers that should be visible at the top of the
    /// message.
    ///
    /// If a given header is not found in the message, it will not be
    /// visible. If no header is given, defaults to the one set up in
    /// your TOML configuration file.
    #[arg(long = "header", short = 'H', value_name = "NAME")]
    #[arg(conflicts_with = "raw")]
    #[arg(conflicts_with = "no_headers")]
    pub headers: Vec<String>,

    #[cfg(feature = "sync")]
    #[command(flatten)]
    pub cache: CacheDisableFlag,

    #[command(flatten)]
    pub account: AccountNameFlag,
}

impl MessageReadCommand {
    pub async fn execute(self, printer: &mut impl Printer, config: &TomlConfig) -> Result<()> {
        info!("executing read message(s) command");

        let folder = &self.folder.name;
        let ids = &self.envelopes.ids;

        let (toml_account_config, account_config) = config.clone().into_account_configs(
            self.account.name.as_ref().map(String::as_str),
            #[cfg(feature = "sync")]
            self.cache.disable,
        )?;

        let get_messages_kind = toml_account_config.get_messages_kind();

        let backend = Backend::new(
            &toml_account_config,
            &account_config,
            get_messages_kind,
            |builder| match get_messages_kind {
                #[cfg(feature = "imap")]
                Some(BackendKind::Imap) => {
                    builder
                        .set_peek_messages(|ctx| ctx.imap.as_ref().and_then(PeekMessagesImap::new));
                    builder
                        .set_get_messages(|ctx| ctx.imap.as_ref().and_then(GetMessagesImap::new));
                }
                #[cfg(feature = "maildir")]
                Some(BackendKind::Maildir) => {
                    builder.set_peek_messages(|ctx| {
                        ctx.maildir.as_ref().and_then(PeekMessagesMaildir::new)
                    });
                    builder
                        .set_add_flags(|ctx| ctx.maildir.as_ref().and_then(AddFlagsMaildir::new));
                }
                #[cfg(feature = "sync")]
                Some(BackendKind::MaildirForSync) => {
                    builder.set_peek_messages(|ctx| {
                        ctx.maildir_for_sync
                            .as_ref()
                            .and_then(PeekMessagesMaildir::new)
                    });
                    builder.set_add_flags(|ctx| {
                        ctx.maildir_for_sync.as_ref().and_then(AddFlagsMaildir::new)
                    });
                }
                _ => (),
            },
        )
        .await?;

        let emails = if self.preview {
            backend.peek_messages(&folder, &ids).await
        } else {
            backend.get_messages(&folder, &ids).await
        }?;

        let mut glue = "";
        let mut bodies = String::default();

        for email in emails.to_vec() {
            bodies.push_str(glue);

            if self.raw {
                // emails do not always have valid utf8, uses "lossy" to
                // display what can be displayed
                bodies.push_str(&String::from_utf8_lossy(email.raw()?).into_owned());
            } else {
                let tpl: String = email
                    .to_read_tpl(&account_config, |mut tpl| {
                        if self.no_headers {
                            tpl = tpl.with_hide_all_headers();
                        } else if !self.headers.is_empty() {
                            tpl = tpl.with_show_only_headers(&self.headers);
                        }

                        if self.html {
                            tpl = tpl.with_filter_parts(FilterParts::Only("text/html".into()));
                        }

                        tpl
                    })
                    .await?
                    .into();
                bodies.push_str(&tpl);
            }

            glue = "\n\n";
        }

        printer.print(bodies)
    }
}