use std::collections::HashSet;
use std::path::{Path, PathBuf};

use elefren::AppData;

use crate::error::GroupError;
use crate::store::{CommonConfig, DEFAULT_LOCALE_NAME};
use crate::tr::TranslationTable;

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
struct FixedConfig {
    enabled: bool,
    /// Group actor's acct
    acct: String,
    /// elefren data
    appdata: AppData,
    /// configured locale to use
    locale: String,
    /// Server's character limit
    character_limit: usize,
    #[serde(skip)]
    _dirty: bool,
    #[serde(skip)]
    _path: PathBuf,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
struct MutableConfig {
    /// Hashtags the group will auto-boost from it's members
    group_tags: HashSet<String>,
    /// List of admin account "acct" names, e.g. piggo@piggo.space
    admin_users: HashSet<String>,
    /// List of users allowed to post to the group, if it is member-only
    member_users: HashSet<String>,
    /// List of users banned from posting to the group
    banned_users: HashSet<String>,
    /// Users who decided they don't want to be shared to the group (does not apply to members)
    optout_users: HashSet<String>,
    /// True if only members should be allowed to write
    member_only: bool,
    /// Banned domain names, e.g. kiwifarms.cc
    banned_servers: HashSet<String>,
    #[serde(skip)]
    _dirty: bool,
    #[serde(skip)]
    _path: PathBuf,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
struct StateConfig {
    /// Last seen notification timestamp (millis)
    last_notif_ts: u64,
    /// Last seen status timestamp (millis)
    last_status_ts: u64,
    #[serde(skip)]
    _dirty: bool,
    #[serde(skip)]
    _path: PathBuf,
}

/// This is the inner data struct holding a group's config
#[derive(Debug, Clone)]
pub struct GroupConfig {
    /// Fixed config that we only read
    config: FixedConfig,
    /// Mutable config we can write
    control: MutableConfig,
    /// State config with timestamps and transient data that is changed frequently
    state: StateConfig,
    /// Group-specific translation table; this is a clone of the global table with group-specific overrides applied.
    _group_tr: TranslationTable,
}

impl Default for FixedConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            acct: "".to_string(),
            locale: DEFAULT_LOCALE_NAME.to_string(),
            appdata: AppData {
                base: Default::default(),
                client_id: Default::default(),
                client_secret: Default::default(),
                redirect: Default::default(),
                token: Default::default(),
            },
            character_limit: 5000,
            _dirty: false,
            _path: PathBuf::default(),
        }
    }
}

impl Default for MutableConfig {
    fn default() -> Self {
        Self {
            group_tags: Default::default(),
            admin_users: Default::default(),
            member_users: Default::default(),
            banned_users: Default::default(),
            optout_users: Default::default(),
            member_only: false,
            banned_servers: Default::default(),
            _dirty: false,
            _path: PathBuf::default(),
        }
    }
}

impl Default for StateConfig {
    fn default() -> Self {
        Self {
            last_notif_ts: 0,
            last_status_ts: 0,
            _dirty: false,
            _path: PathBuf::default(),
        }
    }
}

macro_rules! impl_change_tracking {
    ($struc:ident) => {
        impl $struc {
            pub(crate) fn mark_dirty(&mut self) {
                self._dirty = true;
            }

            pub(crate) fn is_dirty(&self) -> bool {
                self._dirty
            }

            pub(crate) fn clear_dirty_status(&mut self) {
                self._dirty = false;
            }

            pub(crate) async fn save_if_needed(&mut self) -> Result<bool, GroupError> {
                if self.is_dirty() {
                    self.save().await?;
                    Ok(true)
                } else {
                    Ok(false)
                }
            }

            pub(crate) async fn save(&mut self) -> Result<(), GroupError> {
                tokio::fs::write(&self._path, serde_json::to_string_pretty(&self)?.as_bytes()).await?;
                self.clear_dirty_status();
                Ok(())
            }
        }
    };
}

impl_change_tracking!(FixedConfig);
impl_change_tracking!(MutableConfig);
impl_change_tracking!(StateConfig);

async fn load_or_create_control_file(control_path: impl AsRef<Path>) -> Result<MutableConfig, GroupError> {
    let control_path = control_path.as_ref();
    let mut dirty = false;
    let mut control: MutableConfig = if control_path.is_file() {
        let f = tokio::fs::read(&control_path).await?;
        let mut control: MutableConfig = json5::from_str(&String::from_utf8_lossy(&f))?;
        control._path = control_path.to_owned();
        control
    } else {
        debug!("control file missing, creating empty");
        dirty = true;
        MutableConfig {
            _path: control_path.to_owned(),
            ..Default::default()
        }
    };
    if dirty {
        control.save().await?;
    }
    Ok(control)
}

async fn load_or_create_state_file(state_path: impl AsRef<Path>) -> Result<StateConfig, GroupError> {
    let state_path = state_path.as_ref();
    let mut dirty = false;
    let mut state: StateConfig = if state_path.is_file() {
        let f = tokio::fs::read(&state_path).await?;
        let mut control: StateConfig = json5::from_str(&String::from_utf8_lossy(&f))?;
        control._path = state_path.to_owned();
        control
    } else {
        debug!("state file missing, creating empty");
        dirty = true;
        StateConfig {
            _path: state_path.to_owned(),
            ..Default::default()
        }
    };
    if dirty {
        state.save().await?;
    }
    Ok(state)
}

async fn load_locale_override_file(locale_path: impl AsRef<Path>) -> Result<Option<TranslationTable>, GroupError> {
    let locale_path = locale_path.as_ref();
    if locale_path.is_file() {
        let f = tokio::fs::read(&locale_path).await?;
        let opt: TranslationTable = json5::from_str(&String::from_utf8_lossy(&f))?;
        Ok(Some(opt))
    } else {
        Ok(None)
    }
}

impl GroupConfig {
    pub fn tr(&self) -> &TranslationTable {
        &self._group_tr
    }

    pub(crate) fn is_dirty(&self) -> bool {
        self.config.is_dirty() || self.control.is_dirty() || self.state.is_dirty()
    }

    /// Save only what changed
    pub(crate) async fn save_if_needed(&mut self, danger_allow_overwriting_config: bool) -> Result<(), GroupError> {
        #[allow(clippy::collapsible_if)]
        if danger_allow_overwriting_config {
            if self.config.save_if_needed().await? {
                debug!(
                    "Written {} config file {}",
                    self.config.acct,
                    self.config._path.display()
                );
            }
        }
        if self.control.save_if_needed().await? {
            debug!(
                "Written {} control file {}",
                self.config.acct,
                self.control._path.display()
            );
        }
        if self.state.save_if_needed().await? {
            debug!("Written {} state file {}", self.config.acct, self.state._path.display());
        }
        Ok(())
    }

    /// Save all unconditionally
    #[allow(unused)]
    pub(crate) async fn save(&mut self, danger_allow_overwriting_config: bool) -> Result<(), GroupError> {
        if danger_allow_overwriting_config {
            self.config.save().await?;
        }
        self.control.save().await?;
        self.state.save().await?;
        Ok(())
    }

    /// (re)init using new authorization
    pub(crate) async fn initialize_by_appdata(
        acct: String,
        appdata: AppData,
        group_dir: PathBuf,
    ) -> Result<(), GroupError> {
        if !group_dir.is_dir() {
            debug!("Creating group directory");
            tokio::fs::create_dir_all(&group_dir).await?;
        }

        let config_path = group_dir.join("config.json");
        let control_path = group_dir.join("control.json");
        let state_path = group_dir.join("state.json");

        // try to reuse content of the files, if present

        /* config */
        let mut dirty = false;
        let mut config: FixedConfig = if config_path.is_file() {
            let f = tokio::fs::read(&config_path).await?;
            let mut config: FixedConfig = json5::from_str(&String::from_utf8_lossy(&f))?;
            config._path = config_path;
            if config.appdata != appdata {
                config.appdata = appdata;
                dirty = true;
            }
            if config.acct != acct {
                config.acct = acct.clone();
                dirty = true;
            }
            config
        } else {
            dirty = true;
            FixedConfig {
                acct: acct.clone(),
                appdata,
                _path: config_path,
                ..Default::default()
            }
        };
        if dirty {
            debug!("config file for {} changed, creating/updating", acct);
            config.save().await?;
        }

        /* control */
        let control = load_or_create_control_file(control_path).await?;

        /* state */
        let state = load_or_create_state_file(state_path).await?;

        let g = GroupConfig {
            config,
            control,
            state,
            _group_tr: TranslationTable::new(),
        };
        g.warn_of_bad_config();
        Ok(())
    }

    pub(crate) async fn from_dir(group_dir: PathBuf, cc: &CommonConfig) -> Result<Self, GroupError> {
        let config_path = group_dir.join("config.json");
        let control_path = group_dir.join("control.json");
        let state_path = group_dir.join("state.json");
        let locale_path = group_dir.join("messages.json");

        // try to reuse content of the files, if present

        /* config */
        let f = tokio::fs::read(&config_path).await?;
        let mut config: FixedConfig = json5::from_str(&String::from_utf8_lossy(&f))?;
        config._path = config_path;

        /* control */
        let control = load_or_create_control_file(control_path).await?;

        /* state */
        let state = load_or_create_state_file(state_path).await?;

        /* translation table */
        let mut tr = cc.tr(&config.locale).clone();
        if let Some(locale_overrides) = load_locale_override_file(locale_path).await? {
            for (k, v) in locale_overrides.entries() {
                tr.add_translation(k, v);
            }
        }

        let g = GroupConfig {
            config,
            control,
            state,
            _group_tr: tr,
        };
        g.warn_of_bad_config();
        Ok(g)
    }

    fn warn_of_bad_config(&self) {
        for t in &self.control.group_tags {
            if &t.to_lowercase() != t {
                warn!(
                    "Group {} hashtag \"{}\" is not lowercase, it won't work!",
                    self.config.acct, t
                );
            }
        }

        for u in self
            .control
            .admin_users
            .iter()
            .chain(self.control.member_users.iter())
            .chain(self.control.banned_users.iter())
            .chain(self.control.optout_users.iter())
        {
            if &u.to_lowercase() != u {
                warn!(
                    "Group {} config contains a user with non-lowercase name \"{}\", it won't work!",
                    self.config.acct, u
                );
            }

            if u.starts_with('@') || u.chars().filter(|c| *c == '@').count() != 1 {
                warn!("Group {} config contains an invalid user name: {}", self.config.acct, u);
            }
        }
    }

    pub(crate) fn get_character_limit(&self) -> usize {
        self.config.character_limit
    }

    pub(crate) fn is_enabled(&self) -> bool {
        self.config.enabled
    }

    pub(crate) fn get_appdata(&self) -> &AppData {
        &self.config.appdata
    }

    pub(crate) fn set_appdata(&mut self, appdata: AppData) {
        if self.config.appdata != appdata {
            self.config.mark_dirty();
        }
        self.config.appdata = appdata;
    }

    pub(crate) fn get_admins(&self) -> impl Iterator<Item = &String> {
        self.control.admin_users.iter()
    }

    pub(crate) fn get_members(&self) -> impl Iterator<Item = &String> {
        self.control.member_users.iter()
    }

    pub(crate) fn get_tags(&self) -> impl Iterator<Item = &String> {
        self.control.group_tags.iter()
    }

    pub(crate) fn set_last_notif(&mut self, ts: u64) {
        if self.state.last_notif_ts != ts {
            self.state.mark_dirty();
        }
        self.state.last_notif_ts = self.state.last_notif_ts.max(ts);
    }

    pub(crate) fn get_last_notif(&self) -> u64 {
        self.state.last_notif_ts
    }

    pub(crate) fn set_last_status(&mut self, ts: u64) {
        if self.state.last_status_ts != ts {
            self.state.mark_dirty();
        }
        self.state.last_status_ts = self.state.last_status_ts.max(ts);
    }

    pub(crate) fn get_last_status(&self) -> u64 {
        self.state.last_status_ts
    }

    pub(crate) fn get_acct(&self) -> &str {
        &self.config.acct
    }

    pub(crate) fn is_optout(&self, acct: &str) -> bool {
        self.control.optout_users.contains(acct)
    }

    pub(crate) fn is_admin(&self, acct: &str) -> bool {
        self.control.admin_users.contains(acct)
    }

    pub(crate) fn is_member(&self, acct: &str) -> bool {
        self.control.member_users.contains(acct)
    }

    pub(crate) fn is_member_or_admin(&self, acct: &str) -> bool {
        self.is_member(acct) || self.is_admin(acct)
    }

    pub(crate) fn is_banned(&self, acct: &str) -> bool {
        self.control.banned_users.contains(acct) || self.is_users_server_banned(acct)
    }

    pub(crate) fn is_server_banned(&self, server: &str) -> bool {
        self.control.banned_servers.contains(server)
    }

    /// Check if the user's server is banned
    fn is_users_server_banned(&self, acct: &str) -> bool {
        let server = acct_to_server(acct);
        self.is_server_banned(&server)
    }

    pub(crate) fn can_write(&self, acct: &str) -> bool {
        if self.is_admin(acct) {
            true
        } else {
            !self.is_banned(acct) && (!self.is_member_only() || self.is_member(acct))
        }
    }

    pub(crate) fn set_admin(&mut self, acct: &str, admin: bool) -> Result<(), GroupError> {
        let change = if admin {
            if self.is_banned(acct) {
                return Err(GroupError::UserIsBanned);
            }
            self.control.admin_users.insert(acct.to_owned())
        } else {
            self.control.admin_users.remove(acct)
        };
        if change {
            self.control.mark_dirty();
        }
        Ok(())
    }

    pub(crate) fn set_member(&mut self, acct: &str, member: bool) -> Result<(), GroupError> {
        let change = if member {
            if self.is_banned(acct) {
                return Err(GroupError::UserIsBanned);
            }
            self.control.member_users.insert(acct.to_owned())
        } else {
            self.control.member_users.remove(acct)
        };
        if change {
            self.control.mark_dirty();
        }
        Ok(())
    }

    pub(crate) fn set_optout(&mut self, acct: &str, optout: bool) {
        let change = if optout {
            self.control.optout_users.insert(acct.to_owned())
        } else {
            self.control.optout_users.remove(acct)
        };
        if change {
            self.control.mark_dirty();
        }
    }

    pub(crate) fn ban_user(&mut self, acct: &str, ban: bool) -> Result<(), GroupError> {
        let mut change = false;
        if ban {
            if self.is_admin(acct) {
                return Err(GroupError::UserIsAdmin);
            }
            // Banned user is also kicked
            change |= self.control.member_users.remove(acct);
            change |= self.control.banned_users.insert(acct.to_owned());
        } else {
            change |= self.control.banned_users.remove(acct);
        }
        if change {
            self.control.mark_dirty();
        }
        Ok(())
    }

    pub(crate) fn ban_server(&mut self, server: &str, ban: bool) -> Result<(), GroupError> {
        let changed = if ban {
            for acct in &self.control.admin_users {
                let acct_server = acct_to_server(acct);
                if acct_server == server {
                    return Err(GroupError::AdminsOnServer);
                }
            }
            self.control.banned_servers.insert(server.to_owned())
        } else {
            self.control.banned_servers.remove(server)
        };
        if changed {
            self.control.mark_dirty();
        }
        Ok(())
    }

    pub(crate) fn add_tag(&mut self, tag: &str) {
        if self.control.group_tags.insert(tag.to_string()) {
            self.control.mark_dirty();
        }
    }

    pub(crate) fn remove_tag(&mut self, tag: &str) {
        if self.control.group_tags.remove(tag) {
            self.control.mark_dirty();
        }
    }

    pub(crate) fn is_tag_followed(&self, tag: &str) -> bool {
        self.control.group_tags.contains(tag)
    }

    pub(crate) fn set_member_only(&mut self, member_only: bool) {
        if self.control.member_only != member_only {
            self.control.mark_dirty();
        }
        self.control.member_only = member_only;
    }

    pub(crate) fn is_member_only(&self) -> bool {
        self.control.member_only
    }
}

fn acct_to_server(acct: &str) -> String {
    crate::utils::acct_to_server(acct).unwrap_or_default()
}

#[cfg(test)]
mod tests {
    use crate::error::GroupError;
    use crate::store::group_config::{acct_to_server, GroupConfig};

    fn empty_group_config() -> GroupConfig {
        GroupConfig {
            config: Default::default(),
            control: Default::default(),
            state: Default::default(),
            _group_tr: Default::default(),
        }
    }

    #[test]
    fn test_acct_to_server() {
        assert_eq!("pikachu.rocks".to_string(), acct_to_server("raichu@pikachu.rocks"));
        assert_eq!("pikachu.rocks".to_string(), acct_to_server("m@pikachu.rocks"));
        assert_eq!("".to_string(), acct_to_server("what"));
    }

    #[test]
    fn test_default_rules() {
        let group = empty_group_config();
        assert!(!group.is_member_only());
        assert!(!group.is_member("piggo@piggo.space"));
        assert!(!group.is_admin("piggo@piggo.space"));
        assert!(group.can_write("piggo@piggo.space"), "anyone can post by default");
    }

    #[test]
    fn test_member_only() {
        let mut group = empty_group_config();
        assert!(group.can_write("piggo@piggo.space"), "rando can write in public group");

        group.set_member_only(true);
        assert!(
            !group.can_write("piggo@piggo.space"),
            "rando can't write in member-only group"
        );

        // Admin in member only
        group.set_admin("piggo@piggo.space", true).unwrap();
        assert!(
            group.can_write("piggo@piggo.space"),
            "admin non-member can write in member-only group"
        );
        group.set_admin("piggo@piggo.space", false).unwrap();
        assert!(
            !group.can_write("piggo@piggo.space"),
            "removed admin removes privileged write access"
        );

        // Member in member only
        group.set_member("piggo@piggo.space", true).unwrap();
        assert!(
            group.can_write("piggo@piggo.space"),
            "member can post in member-only group"
        );
        group.set_admin("piggo@piggo.space", true).unwrap();
        assert!(
            group.can_write("piggo@piggo.space"),
            "member+admin can post in member-only group"
        );
    }

    #[test]
    fn test_banned_users() {
        // Banning single user
        let mut group = empty_group_config();
        group.ban_user("piggo@piggo.space", true).unwrap();
        assert!(!group.can_write("piggo@piggo.space"), "banned user can't post");
        group.ban_user("piggo@piggo.space", false).unwrap();
        assert!(group.can_write("piggo@piggo.space"), "un-ban works");
    }

    #[test]
    fn test_banned_members() {
        // Banning single user
        let mut group = empty_group_config();
        group.set_member_only(true);

        group.set_member("piggo@piggo.space", true).unwrap();
        assert!(group.can_write("piggo@piggo.space"), "member can write");
        assert!(group.is_member("piggo@piggo.space"), "member is member");
        assert!(!group.is_banned("piggo@piggo.space"), "user not banned by default");

        group.ban_user("piggo@piggo.space", true).unwrap();
        assert!(!group.is_member("piggo@piggo.space"), "banned user is kicked");
        assert!(group.is_banned("piggo@piggo.space"), "banned user is banned");

        assert!(!group.can_write("piggo@piggo.space"), "banned member can't post");

        // unban
        group.ban_user("piggo@piggo.space", false).unwrap();
        assert!(!group.can_write("piggo@piggo.space"), "unbanned member is still kicked");
        group.set_member("piggo@piggo.space", true).unwrap();
        assert!(group.can_write("piggo@piggo.space"), "un-ban works");
    }

    #[test]
    fn test_server_ban() {
        let mut group = empty_group_config();
        assert!(group.can_write("hitler@nazi.camp"), "randos can write");

        group.ban_server("nazi.camp", true).unwrap();
        assert!(
            !group.can_write("hitler@nazi.camp"),
            "users from banned server can't write"
        );
        assert!(
            !group.can_write("1488@nazi.camp"),
            "users from banned server can't write"
        );
        assert!(group.can_write("troll@freezepeach.xyz"), "other users can still write");

        group.ban_server("nazi.camp", false).unwrap();
        assert!(group.can_write("hitler@nazi.camp"), "server unban works");
    }

    #[test]
    fn test_sanity() {
        let mut group = empty_group_config();

        group.set_admin("piggo@piggo.space", true).unwrap();
        assert_eq!(
            Err(GroupError::UserIsAdmin),
            group.ban_user("piggo@piggo.space", true),
            "can't bad admin users"
        );
        group.ban_user("piggo@piggo.space", false).expect("can unbad admin");

        group.ban_user("hitler@nazi.camp", true).unwrap();
        assert_eq!(
            Err(GroupError::UserIsBanned),
            group.set_admin("hitler@nazi.camp", true),
            "can't make banned users admins"
        );

        group.ban_server("freespeechextremist.com", true).unwrap();
        assert_eq!(
            Err(GroupError::UserIsBanned),
            group.set_admin("nibber@freespeechextremist.com", true),
            "can't make server-banned users admins"
        );

        assert!(group.is_admin("piggo@piggo.space"));
        assert_eq!(
            Err(GroupError::AdminsOnServer),
            group.ban_server("piggo.space", true),
            "can't bad server with admins"
        );
    }
}