//! # Email accounts autoconfiguration process.
//!
//! The module provides automatic lookup of configuration
//! for email providers based on the built-in [provider database],
//! [Mozilla Thunderbird Autoconfiguration protocol]
//! and [Outlook's Autodiscover].
//!
//! [provider database]: crate::provider
//! [Mozilla Thunderbird Autoconfiguration protocol]: auto_mozilla
//! [Outlook's Autodiscover]: auto_outlook

mod auto_mozilla;
mod auto_outlook;
pub(crate) mod server_params;

use anyhow::{bail, ensure, format_err, Context as _, Result};
use auto_mozilla::moz_autoconfigure;
use auto_outlook::outlk_autodiscover;
use deltachat_contact_tools::EmailAddress;
use futures::FutureExt;
use futures_lite::FutureExt as _;
use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
use server_params::{expand_param_vector, ServerParams};
use tokio::task;

use crate::config::{self, Config};
use crate::context::Context;
use crate::imap::Imap;
use crate::log::LogExt;
use crate::login_param::{
    ConfiguredCertificateChecks, ConfiguredLoginParam, ConfiguredServerLoginParam,
    ConnectionCandidate, EnteredCertificateChecks, EnteredLoginParam,
};
use crate::message::{Message, Viewtype};
use crate::oauth2::get_oauth2_addr;
use crate::provider::{Protocol, Socket, UsernamePattern};
use crate::smtp::Smtp;
use crate::stock_str;
use crate::sync::Sync::*;
use crate::tools::time;
use crate::{chat, e2ee, provider};
use deltachat_contact_tools::addr_cmp;

macro_rules! progress {
    ($context:tt, $progress:expr, $comment:expr) => {
        assert!(
            $progress <= 1000,
            "value in range 0..1000 expected with: 0=error, 1..999=progress, 1000=success"
        );
        $context.emit_event($crate::events::EventType::ConfigureProgress {
            progress: $progress,
            comment: $comment,
        });
    };
    ($context:tt, $progress:expr) => {
        progress!($context, $progress, None);
    };
}

impl Context {
    /// Checks if the context is already configured.
    pub async fn is_configured(&self) -> Result<bool> {
        self.sql
            .get_raw_config_bool("configured")
            .await
            .map_err(Into::into)
    }

    /// Configures this account with the currently set parameters.
    pub async fn configure(&self) -> Result<()> {
        ensure!(
            !self.scheduler.is_running().await,
            "cannot configure, already running"
        );
        ensure!(
            self.sql.is_open().await,
            "cannot configure, database not opened."
        );
        let cancel_channel = self.alloc_ongoing().await?;

        let res = self
            .inner_configure()
            .race(cancel_channel.recv().map(|_| Err(format_err!("Cancelled"))))
            .await;

        self.free_ongoing().await;

        if let Err(err) = res.as_ref() {
            progress!(
                self,
                0,
                Some(
                    stock_str::configuration_failed(
                        self,
                        // We are using Anyhow's .context() and to show the
                        // inner error, too, we need the {:#}:
                        &format!("{err:#}"),
                    )
                    .await
                )
            );
        } else {
            progress!(self, 1000);
        }

        res
    }

    async fn inner_configure(&self) -> Result<()> {
        info!(self, "Configure ...");

        let param = EnteredLoginParam::load(self).await?;
        let old_addr = self.get_config(Config::ConfiguredAddr).await?;

        let configured_param_res = configure(self, &param).await;
        self.set_config_internal(Config::NotifyAboutWrongPw, None)
            .await?;

        on_configure_completed(self, configured_param_res?, old_addr).await?;

        self.set_config_internal(Config::NotifyAboutWrongPw, Some("1"))
            .await?;
        Ok(())
    }
}

async fn on_configure_completed(
    context: &Context,
    param: ConfiguredLoginParam,
    old_addr: Option<String>,
) -> Result<()> {
    if let Some(provider) = param.provider {
        if let Some(config_defaults) = provider.config_defaults {
            for def in config_defaults {
                if !context.config_exists(def.key).await? {
                    info!(context, "apply config_defaults {}={}", def.key, def.value);
                    context
                        .set_config_ex(Nosync, def.key, Some(def.value))
                        .await?;
                } else {
                    info!(
                        context,
                        "skip already set config_defaults {}={}", def.key, def.value
                    );
                }
            }
        }

        if !provider.after_login_hint.is_empty() {
            let mut msg = Message::new(Viewtype::Text);
            msg.text = provider.after_login_hint.to_string();
            if chat::add_device_msg(context, Some("core-provider-info"), Some(&mut msg))
                .await
                .is_err()
            {
                warn!(context, "cannot add after_login_hint as core-provider-info");
            }
        }
    }

    if let Some(new_addr) = context.get_config(Config::ConfiguredAddr).await? {
        if let Some(old_addr) = old_addr {
            if !addr_cmp(&new_addr, &old_addr) {
                let mut msg = Message::new(Viewtype::Text);
                msg.text =
                    stock_str::aeap_explanation_and_link(context, &old_addr, &new_addr).await;
                chat::add_device_msg(context, None, Some(&mut msg))
                    .await
                    .context("Cannot add AEAP explanation")
                    .log_err(context)
                    .ok();
            }
        }
    }

    Ok(())
}

/// Retrieves data from autoconfig and provider database
/// to transform user-entered login parameters into complete configuration.
async fn get_configured_param(
    ctx: &Context,
    param: &EnteredLoginParam,
) -> Result<ConfiguredLoginParam> {
    ensure!(!param.addr.is_empty(), "Missing email address.");

    ensure!(!param.imap.password.is_empty(), "Missing (IMAP) password.");

    // SMTP password is an "advanced" setting. If unset, use the same password as for IMAP.
    let smtp_password = if param.smtp.password.is_empty() {
        param.imap.password.clone()
    } else {
        param.smtp.password.clone()
    };

    let proxy_config = param.proxy_config.clone();
    let proxy_enabled = proxy_config.is_some();

    let mut addr = param.addr.clone();
    if param.oauth2 {
        // the used oauth2 addr may differ, check this.
        // if get_oauth2_addr() is not available in the oauth2 implementation, just use the given one.
        progress!(ctx, 10);
        if let Some(oauth2_addr) = get_oauth2_addr(ctx, &param.addr, &param.imap.password)
            .await?
            .and_then(|e| e.parse().ok())
        {
            info!(ctx, "Authorized address is {}", oauth2_addr);
            addr = oauth2_addr;
            ctx.sql
                .set_raw_config("addr", Some(param.addr.as_str()))
                .await?;
        }
        progress!(ctx, 20);
    }
    // no oauth? - just continue it's no error

    let parsed = EmailAddress::new(&param.addr).context("Bad email-address")?;
    let param_domain = parsed.domain;

    progress!(ctx, 200);

    let provider;
    let param_autoconfig;
    if param.imap.server.is_empty()
        && param.imap.port == 0
        && param.imap.security == Socket::Automatic
        && param.imap.user.is_empty()
        && param.smtp.server.is_empty()
        && param.smtp.port == 0
        && param.smtp.security == Socket::Automatic
        && param.smtp.user.is_empty()
    {
        // no advanced parameters entered by the user: query provider-database or do Autoconfig
        info!(
            ctx,
            "checking internal provider-info for offline autoconfig"
        );

        provider = provider::get_provider_info(ctx, &param_domain, proxy_enabled).await;
        if let Some(provider) = provider {
            if provider.server.is_empty() {
                info!(ctx, "Offline autoconfig found, but no servers defined.");
                param_autoconfig = None;
            } else {
                info!(ctx, "Offline autoconfig found.");
                let servers = provider
                    .server
                    .iter()
                    .map(|s| ServerParams {
                        protocol: s.protocol,
                        socket: s.socket,
                        hostname: s.hostname.to_string(),
                        port: s.port,
                        username: match s.username_pattern {
                            UsernamePattern::Email => param.addr.to_string(),
                            UsernamePattern::Emaillocalpart => {
                                if let Some(at) = param.addr.find('@') {
                                    param.addr.split_at(at).0.to_string()
                                } else {
                                    param.addr.to_string()
                                }
                            }
                        },
                    })
                    .collect();

                param_autoconfig = Some(servers)
            }
        } else {
            // Try receiving autoconfig
            info!(ctx, "No offline autoconfig found.");
            param_autoconfig = get_autoconfig(ctx, param, &param_domain).await;
        }
    } else {
        provider = None;
        param_autoconfig = None;
    }

    progress!(ctx, 500);

    let mut servers = param_autoconfig.unwrap_or_default();
    if !servers
        .iter()
        .any(|server| server.protocol == Protocol::Imap)
    {
        servers.push(ServerParams {
            protocol: Protocol::Imap,
            hostname: param.imap.server.clone(),
            port: param.imap.port,
            socket: param.imap.security,
            username: param.imap.user.clone(),
        })
    }
    if !servers
        .iter()
        .any(|server| server.protocol == Protocol::Smtp)
    {
        servers.push(ServerParams {
            protocol: Protocol::Smtp,
            hostname: param.smtp.server.clone(),
            port: param.smtp.port,
            socket: param.smtp.security,
            username: param.smtp.user.clone(),
        })
    }

    let servers = expand_param_vector(servers, &param.addr, &param_domain);

    let configured_login_param = ConfiguredLoginParam {
        addr,
        imap: servers
            .iter()
            .filter_map(|params| {
                let Ok(security) = params.socket.try_into() else {
                    return None;
                };
                if params.protocol == Protocol::Imap {
                    Some(ConfiguredServerLoginParam {
                        connection: ConnectionCandidate {
                            host: params.hostname.clone(),
                            port: params.port,
                            security,
                        },
                        user: params.username.clone(),
                    })
                } else {
                    None
                }
            })
            .collect(),
        imap_user: param.imap.user.clone(),
        imap_password: param.imap.password.clone(),
        smtp: servers
            .iter()
            .filter_map(|params| {
                let Ok(security) = params.socket.try_into() else {
                    return None;
                };
                if params.protocol == Protocol::Smtp {
                    Some(ConfiguredServerLoginParam {
                        connection: ConnectionCandidate {
                            host: params.hostname.clone(),
                            port: params.port,
                            security,
                        },
                        user: params.username.clone(),
                    })
                } else {
                    None
                }
            })
            .collect(),
        smtp_user: param.smtp.user.clone(),
        smtp_password,
        proxy_config: param.proxy_config.clone(),
        provider,
        certificate_checks: match param.certificate_checks {
            EnteredCertificateChecks::Automatic => ConfiguredCertificateChecks::Automatic,
            EnteredCertificateChecks::Strict => ConfiguredCertificateChecks::Strict,
            EnteredCertificateChecks::AcceptInvalidCertificates
            | EnteredCertificateChecks::AcceptInvalidCertificates2 => {
                ConfiguredCertificateChecks::AcceptInvalidCertificates
            }
        },
        oauth2: param.oauth2,
    };
    Ok(configured_login_param)
}

async fn configure(ctx: &Context, param: &EnteredLoginParam) -> Result<ConfiguredLoginParam> {
    progress!(ctx, 1);

    let ctx2 = ctx.clone();
    let update_device_chats_handle = task::spawn(async move { ctx2.update_device_chats().await });

    let configured_param = get_configured_param(ctx, param).await?;
    let strict_tls = configured_param.strict_tls();

    progress!(ctx, 550);

    // Spawn SMTP configuration task
    // to try SMTP while connecting to IMAP.
    let context_smtp = ctx.clone();
    let smtp_param = configured_param.smtp.clone();
    let smtp_password = configured_param.smtp_password.clone();
    let smtp_addr = configured_param.addr.clone();
    let proxy_config = configured_param.proxy_config.clone();

    let smtp_config_task = task::spawn(async move {
        let mut smtp = Smtp::new();
        smtp.connect(
            &context_smtp,
            &smtp_param,
            &smtp_password,
            &proxy_config,
            &smtp_addr,
            strict_tls,
            configured_param.oauth2,
        )
        .await?;

        Ok::<(), anyhow::Error>(())
    });

    progress!(ctx, 600);

    // Configure IMAP

    let (_s, r) = async_channel::bounded(1);
    let mut imap = Imap::new(
        configured_param.imap.clone(),
        configured_param.imap_password.clone(),
        configured_param.proxy_config.clone(),
        &configured_param.addr,
        strict_tls,
        configured_param.oauth2,
        r,
    );
    let mut imap_session = match imap.connect(ctx).await {
        Ok(session) => session,
        Err(err) => bail!("{}", nicer_configuration_error(ctx, err.to_string()).await),
    };

    progress!(ctx, 850);

    // Wait for SMTP configuration
    smtp_config_task.await.unwrap()?;

    progress!(ctx, 900);

    let is_chatmail = match ctx.get_config_bool(Config::FixIsChatmail).await? {
        false => {
            let is_chatmail = imap_session.is_chatmail();
            ctx.set_config(
                Config::IsChatmail,
                Some(match is_chatmail {
                    false => "0",
                    true => "1",
                }),
            )
            .await?;
            is_chatmail
        }
        true => ctx.get_config_bool(Config::IsChatmail).await?,
    };
    if is_chatmail {
        ctx.set_config(Config::SentboxWatch, None).await?;
        ctx.set_config(Config::MvboxMove, Some("0")).await?;
        ctx.set_config(Config::OnlyFetchMvbox, None).await?;
        ctx.set_config(Config::ShowEmails, None).await?;
        ctx.set_config(Config::E2eeEnabled, Some("1")).await?;
    }

    let create_mvbox = !is_chatmail;
    imap.configure_folders(ctx, &mut imap_session, create_mvbox)
        .await?;

    imap_session
        .select_with_uidvalidity(ctx, "INBOX")
        .await
        .context("could not read INBOX status")?;

    drop(imap);

    progress!(ctx, 910);

    if let Some(configured_addr) = ctx.get_config(Config::ConfiguredAddr).await? {
        if configured_addr != param.addr {
            // Switched account, all server UIDs we know are invalid
            info!(ctx, "Scheduling resync because the address has changed.");
            ctx.schedule_resync().await?;
        }
    }

    configured_param.save_as_configured_params(ctx).await?;
    ctx.set_config_internal(Config::ConfiguredTimestamp, Some(&time().to_string()))
        .await?;

    progress!(ctx, 920);

    e2ee::ensure_secret_key_exists(ctx).await?;
    info!(ctx, "key generation completed");

    ctx.set_config_internal(Config::FetchedExistingMsgs, config::from_bool(false))
        .await?;
    ctx.scheduler.interrupt_inbox().await;

    progress!(ctx, 940);
    update_device_chats_handle.await??;

    ctx.sql.set_raw_config_bool("configured", true).await?;

    Ok(configured_param)
}

/// Retrieve available autoconfigurations.
///
/// A. Search configurations from the domain used in the email-address
/// B. If we have no configuration yet, search configuration in Thunderbird's central database
async fn get_autoconfig(
    ctx: &Context,
    param: &EnteredLoginParam,
    param_domain: &str,
) -> Option<Vec<ServerParams>> {
    let param_addr_urlencoded = utf8_percent_encode(&param.addr, NON_ALPHANUMERIC).to_string();

    if let Ok(res) = moz_autoconfigure(
        ctx,
        &format!(
            "https://autoconfig.{param_domain}/mail/config-v1.1.xml?emailaddress={param_addr_urlencoded}"
        ),
        &param.addr,
    )
    .await
    {
        return Some(res);
    }
    progress!(ctx, 300);

    if let Ok(res) = moz_autoconfigure(
        ctx,
        // the doc does not mention `emailaddress=`, however, Thunderbird adds it, see <https://releases.mozilla.org/pub/thunderbird/>,  which makes some sense
        &format!(
            "https://{}/.well-known/autoconfig/mail/config-v1.1.xml?emailaddress={}",
            &param_domain, &param_addr_urlencoded
        ),
        &param.addr,
    )
    .await
    {
        return Some(res);
    }
    progress!(ctx, 310);

    // Outlook uses always SSL but different domains (this comment describes the next two steps)
    if let Ok(res) = outlk_autodiscover(
        ctx,
        format!("https://{}/autodiscover/autodiscover.xml", &param_domain),
    )
    .await
    {
        return Some(res);
    }
    progress!(ctx, 320);

    if let Ok(res) = outlk_autodiscover(
        ctx,
        format!(
            "https://autodiscover.{}/autodiscover/autodiscover.xml",
            &param_domain
        ),
    )
    .await
    {
        return Some(res);
    }
    progress!(ctx, 330);

    // always SSL for Thunderbird's database
    if let Ok(res) = moz_autoconfigure(
        ctx,
        &format!("https://autoconfig.thunderbird.net/v1.1/{}", &param_domain),
        &param.addr,
    )
    .await
    {
        return Some(res);
    }

    None
}

async fn nicer_configuration_error(context: &Context, e: String) -> String {
    if e.to_lowercase().contains("could not resolve")
        || e.to_lowercase().contains("connection attempts")
        || e.to_lowercase()
            .contains("temporary failure in name resolution")
        || e.to_lowercase().contains("name or service not known")
        || e.to_lowercase()
            .contains("failed to lookup address information")
    {
        return stock_str::error_no_network(context).await;
    }

    e
}

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("Invalid email address: {0:?}")]
    InvalidEmailAddress(String),

    #[error("XML error at position {position}: {error}")]
    InvalidXml {
        position: u64,
        #[source]
        error: quick_xml::Error,
    },

    #[error("Number of redirection is exceeded")]
    Redirection,

    #[error("{0:#}")]
    Other(#[from] anyhow::Error),
}

#[cfg(test)]
mod tests {
    #![allow(clippy::indexing_slicing)]

    use super::*;
    use crate::config::Config;
    use crate::login_param::EnteredServerLoginParam;
    use crate::test_utils::TestContext;

    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    async fn test_no_panic_on_bad_credentials() {
        let t = TestContext::new().await;
        t.set_config(Config::Addr, Some("probably@unexistant.addr"))
            .await
            .unwrap();
        t.set_config(Config::MailPw, Some("123456")).await.unwrap();
        assert!(t.configure().await.is_err());
    }

    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    async fn test_get_configured_param() -> Result<()> {
        let t = &TestContext::new().await;
        let entered_param = EnteredLoginParam {
            addr: "alice@example.org".to_string(),

            imap: EnteredServerLoginParam {
                user: "alice@example.net".to_string(),
                password: "foobar".to_string(),
                ..Default::default()
            },

            ..Default::default()
        };
        let configured_param = get_configured_param(t, &entered_param).await?;
        assert_eq!(configured_param.imap_user, "alice@example.net");
        assert_eq!(configured_param.smtp_user, "");
        Ok(())
    }
}