use std::collections::HashMap;

use chrono::Utc;
use serde_json::{Value as JsonValue};
use uuid::Uuid;

use mitra_config::Config;
use mitra_utils::{
    html::clean_html,
    urls::get_hostname,
};

use crate::activitypub::{
    constants::{AP_MEDIA_TYPE, AP_PUBLIC, AS_MEDIA_TYPE},
    fetcher::fetchers::{fetch_file, FetchError},
    fetcher::helpers::{
        get_or_import_profile_by_actor_address,
        get_or_import_profile_by_actor_id,
        import_post,
    },
    identifiers::parse_local_actor_id,
    receiver::{parse_array, parse_property_value, HandlerError},
    types::{Attachment, EmojiTag, Link, LinkTag, Object, Tag},
    vocabulary::*,
};
use crate::database::{DatabaseClient, DatabaseError};
use crate::errors::ValidationError;
use crate::models::{
    attachments::queries::create_attachment,
    emojis::queries::{
        create_emoji,
        get_emoji_by_remote_object_id,
        update_emoji,
    },
    emojis::types::EmojiImage,
    emojis::validators::{
        validate_emoji_name,
        EMOJI_MAX_SIZE,
        EMOJI_MEDIA_TYPES,
    },
    posts::{
        hashtags::normalize_hashtag,
        helpers::get_post_by_object_id,
        mentions::mention_to_address,
        queries::create_post,
        types::{Post, PostCreateData, Visibility},
        validators::{
            content_allowed_classes,
            ATTACHMENTS_MAX_NUM,
            CONTENT_MAX_SIZE,
            EMOJIS_MAX_NUM,
        },
    },
    profiles::types::DbActorProfile,
    users::queries::get_user_by_name,
};
use super::HandlerResult;

fn get_object_attributed_to(object: &Object)
    -> Result<String, ValidationError>
{
    let attributed_to = object.attributed_to.as_ref()
        .ok_or(ValidationError("unattributed note"))?;
    let author_id = parse_array(attributed_to)
        .map_err(|_| ValidationError("invalid attributedTo property"))?
        .get(0)
        .ok_or(ValidationError("invalid attributedTo property"))?
        .to_string();
    Ok(author_id)
}

pub fn get_object_url(object: &Object) -> Result<String, ValidationError> {
    let maybe_object_url = match &object.url {
        Some(JsonValue::String(string)) => Some(string.to_owned()),
        Some(other_value) => {
            let links: Vec<Link> = parse_property_value(other_value)
                .map_err(|_| ValidationError("invalid object URL"))?;
            links.get(0).map(|link| link.href.clone())
        },
        None => None,
    };
    let object_url = maybe_object_url.unwrap_or(object.id.clone());
    Ok(object_url)
}

pub fn get_object_content(object: &Object) -> Result<String, ValidationError> {
    let content = if let Some(ref content) = object.content {
        if object.media_type == Some("text/markdown".to_string()) {
            format!("<p>{}</p>", content)
        } else {
            // HTML
            content.to_string()
        }
    } else {
        // Lemmy pages and PeerTube videos have "name" property
        object.name.as_deref().unwrap_or("").to_string()
    };
    if content.len() > CONTENT_MAX_SIZE {
        return Err(ValidationError("content is too long"));
    };
    let content_safe = clean_html(&content, content_allowed_classes());
    Ok(content_safe)
}

pub fn create_content_link(url: String) -> String {
    format!(
        r#"<p><a href="{0}" rel="noopener">{0}</a></p>"#,
        url,
    )
}

fn is_gnu_social_link(author_id: &str, attachment: &Attachment) -> bool {
    if !author_id.contains("/index.php/user/") {
        return false;
    };
    if attachment.attachment_type != DOCUMENT {
        return false;
    };
    match attachment.media_type.as_ref() {
        None => true,
        Some(media_type) if media_type.contains("text/html") => true,
        _ => false,
    }
}

pub async fn get_object_attachments(
    config: &Config,
    db_client: &impl DatabaseClient,
    object: &Object,
    author: &DbActorProfile,
) -> Result<(Vec<Uuid>, Vec<String>), HandlerError> {
    let instance = config.instance();
    let media_dir = config.media_dir();
    let mut attachments = vec![];
    let mut unprocessed = vec![];
    if let Some(ref value) = object.attachment {
        let list: Vec<Attachment> = parse_property_value(value)
            .map_err(|_| ValidationError("invalid attachment property"))?;
        let mut downloaded = vec![];
        for attachment in list {
            match attachment.attachment_type.as_str() {
                DOCUMENT | IMAGE | VIDEO => (),
                _ => {
                    log::warn!(
                        "skipping attachment of type {}",
                        attachment.attachment_type,
                    );
                    continue;
                },
            };
            if is_gnu_social_link(
                &author.actor_id(&instance.url()),
                &attachment,
            ) {
                // Don't fetch HTML pages attached by GNU Social
                continue;
            };
            let attachment_url = attachment.url
                .ok_or(ValidationError("attachment URL is missing"))?;
            let (file_name, file_size, maybe_media_type) = match fetch_file(
                &instance,
                &attachment_url,
                attachment.media_type.as_deref(),
                config.limits.media.file_size_limit,
                &media_dir,
            ).await {
                Ok(file) => file,
                Err(FetchError::FileTooLarge) => {
                    log::warn!("attachment is too large: {}", attachment_url);
                    unprocessed.push(attachment_url);
                    continue;
                },
                Err(other_error) => {
                    log::warn!("{}", other_error);
                    return Err(ValidationError("failed to fetch attachment").into());
                },
            };
            log::info!("downloaded attachment {}", attachment_url);
            downloaded.push((file_name, file_size, maybe_media_type));
            // Stop downloading if limit is reached
            if downloaded.len() >= ATTACHMENTS_MAX_NUM {
                log::warn!("too many attachments");
                break;
            };
        };
        for (file_name, file_size, maybe_media_type) in downloaded {
            let db_attachment = create_attachment(
                db_client,
                &author.id,
                file_name,
                file_size,
                maybe_media_type,
            ).await?;
            attachments.push(db_attachment.id);
        };
    };
    Ok((attachments, unprocessed))
}

pub fn get_object_links(
    object: &Object,
) -> Result<Vec<String>, HandlerError> {
    let mut links = vec![];
    if let Some(ref value) = object.tag {
        let list: Vec<JsonValue> = parse_property_value(value)
            .map_err(|_| ValidationError("invalid tag property"))?;
        for tag_value in list {
            let tag_type = tag_value["type"].as_str().unwrap_or(HASHTAG);
            if tag_type == LINK {
                let tag: LinkTag = match serde_json::from_value(tag_value) {
                    Ok(tag) => tag,
                    Err(_) => {
                        log::warn!("invalid link tag");
                        continue;
                    },
                };
                if tag.media_type != AP_MEDIA_TYPE &&
                    tag.media_type != AS_MEDIA_TYPE
                {
                    // Unknown media type
                    continue;
                };
                if !links.contains(&tag.href) {
                    links.push(tag.href);
                };
            };
        };
    };
    if let Some(ref object_id) = object.quote_url {
        if !links.contains(object_id) {
            links.push(object_id.to_owned());
        };
    };
    Ok(links)
}

pub async fn get_object_tags(
    config: &Config,
    db_client: &impl DatabaseClient,
    object: &Object,
    redirects: &HashMap<String, String>,
) -> Result<(Vec<Uuid>, Vec<String>, Vec<Uuid>, Vec<Uuid>), HandlerError> {
    let instance = config.instance();
    let media_dir = config.media_dir();
    let mut mentions = vec![];
    let mut hashtags = vec![];
    let mut links = vec![];
    let mut emojis = vec![];
    if let Some(ref value) = object.tag {
        let list: Vec<JsonValue> = parse_property_value(value)
            .map_err(|_| ValidationError("invalid tag property"))?;
        for tag_value in list {
            let tag_type = tag_value["type"].as_str().unwrap_or(HASHTAG);
            if tag_type == HASHTAG {
                let tag: Tag = match serde_json::from_value(tag_value) {
                    Ok(tag) => tag,
                    Err(_) => {
                        log::warn!("invalid hashtag");
                        continue;
                    },
                };
                if let Some(tag_name) = tag.name {
                    // Ignore invalid tags
                    if let Ok(tag_name) = normalize_hashtag(&tag_name) {
                        if !hashtags.contains(&tag_name) {
                            hashtags.push(tag_name);
                        };
                    };
                };
            } else if tag_type == MENTION {
                let tag: Tag = match serde_json::from_value(tag_value) {
                    Ok(tag) => tag,
                    Err(_) => {
                        log::warn!("invalid mention");
                        continue;
                    },
                };
                // Try to find profile by actor ID.
                if let Some(href) = tag.href {
                    if let Ok(username) = parse_local_actor_id(&instance.url(), &href) {
                        let user = get_user_by_name(db_client, &username).await?;
                        if !mentions.contains(&user.id) {
                            mentions.push(user.id);
                        };
                        continue;
                    };
                    // NOTE: `href` attribute is usually actor ID
                    // but also can be actor URL (profile link).
                    match get_or_import_profile_by_actor_id(
                        db_client,
                        &instance,
                        &media_dir,
                        &href,
                    ).await {
                        Ok(profile) => {
                            if !mentions.contains(&profile.id) {
                                mentions.push(profile.id);
                            };
                            continue;
                        },
                        Err(error) => {
                            log::warn!(
                                "failed to find mentioned profile by ID {}: {}",
                                href,
                                error,
                            );
                        },
                    };
                };
                // Try to find profile by actor address
                let tag_name = match tag.name {
                    Some(name) => name,
                    None => {
                        log::warn!("failed to parse mention");
                        continue;
                    },
                };
                if let Ok(actor_address) = mention_to_address(&tag_name) {
                    let profile = match get_or_import_profile_by_actor_address(
                        db_client,
                        &instance,
                        &media_dir,
                        &actor_address,
                    ).await {
                        Ok(profile) => profile,
                        Err(error @ (
                            HandlerError::FetchError(_) |
                            HandlerError::DatabaseError(DatabaseError::NotFound(_))
                        )) => {
                            // Ignore mention if fetcher fails
                            // Ignore mention if local address is not valid
                            log::warn!(
                                "failed to find mentioned profile {}: {}",
                                actor_address,
                                error,
                            );
                            continue;
                        },
                        Err(other_error) => return Err(other_error),
                    };
                    if !mentions.contains(&profile.id) {
                        mentions.push(profile.id);
                    };
                } else {
                    log::warn!("failed to parse mention {}", tag_name);
                };
            } else if tag_type == LINK {
                let tag: LinkTag = match serde_json::from_value(tag_value) {
                    Ok(tag) => tag,
                    Err(_) => {
                        log::warn!("invalid link tag");
                        continue;
                    },
                };
                if tag.media_type != AP_MEDIA_TYPE &&
                    tag.media_type != AS_MEDIA_TYPE
                {
                    // Unknown media type
                    continue;
                };
                let href = redirects.get(&tag.href).unwrap_or(&tag.href);
                let linked = get_post_by_object_id(
                    db_client,
                    &instance.url(),
                    href,
                ).await?;
                if !links.contains(&linked.id) {
                    links.push(linked.id);
                };
            } else if tag_type == EMOJI {
                let tag: EmojiTag = match serde_json::from_value(tag_value) {
                    Ok(tag) => tag,
                    Err(error) => {
                        log::warn!("invalid emoji tag: {}", error);
                        continue;
                    },
                };
                if emojis.len() >= EMOJIS_MAX_NUM {
                    log::warn!("too many emojis");
                    continue;
                };
                let tag_name = tag.name.trim_matches(':');
                if validate_emoji_name(tag_name).is_err() {
                    log::warn!("invalid emoji name");
                    continue;
                };
                let maybe_emoji_id = match get_emoji_by_remote_object_id(
                    db_client,
                    &tag.id,
                ).await {
                    Ok(emoji) => {
                        if emoji.updated_at >= tag.updated {
                            // Emoji already exists and is up to date
                            if !emojis.contains(&emoji.id) {
                                emojis.push(emoji.id);
                            };
                            continue;
                        };
                        if emoji.emoji_name != tag_name {
                            log::warn!("emoji name can't be changed");
                            continue;
                        };
                        Some(emoji.id)
                    },
                    Err(DatabaseError::NotFound("emoji")) => None,
                    Err(other_error) => return Err(other_error.into()),
                };
                let (file_name, file_size, maybe_media_type) = match fetch_file(
                    &instance,
                    &tag.icon.url,
                    tag.icon.media_type.as_deref(),
                    EMOJI_MAX_SIZE,
                    &media_dir,
                ).await {
                    Ok(file) => file,
                    Err(error) => {
                        log::warn!("failed to fetch emoji: {}", error);
                        continue;
                    },
                };
                let media_type = match maybe_media_type {
                    Some(media_type) if EMOJI_MEDIA_TYPES.contains(&media_type.as_str()) => {
                        media_type
                    },
                    _ => {
                        log::warn!(
                            "unexpected emoji media type: {:?}",
                            maybe_media_type,
                        );
                        continue;
                    },
                };
                log::info!("downloaded emoji {}", tag.icon.url);
                let image = EmojiImage { file_name, file_size, media_type };
                let emoji = if let Some(emoji_id) = maybe_emoji_id {
                    update_emoji(
                        db_client,
                        &emoji_id,
                        image,
                        &tag.updated,
                    ).await?
                } else {
                    let hostname = get_hostname(&tag.id)
                        .map_err(|_| ValidationError("invalid emoji ID"))?;
                    create_emoji(
                        db_client,
                        tag_name,
                        Some(&hostname),
                        image,
                        Some(&tag.id),
                        &tag.updated,
                    ).await?
                };
                if !emojis.contains(&emoji.id) {
                    emojis.push(emoji.id);
                };
            } else {
                log::warn!(
                    "skipping tag of type {}",
                    tag_type,
                );
            };
        };
    };
    if let Some(ref object_id) = object.quote_url {
        let object_id = redirects.get(object_id).unwrap_or(object_id);
        let linked = get_post_by_object_id(
            db_client,
            &instance.url(),
            object_id,
        ).await?;
        if !links.contains(&linked.id) {
            links.push(linked.id);
        };
    };
    Ok((mentions, hashtags, links, emojis))
}

fn get_object_visibility(
    author: &DbActorProfile,
    primary_audience: Vec<String>,
    secondary_audience: Vec<String>,
) -> Visibility {
    let audience = [primary_audience, secondary_audience].concat();
    // Some servers (e.g. Takahe) use "as" namespace
    const PUBLIC_VARIANTS: [&str; 3] = [
        AP_PUBLIC,
        "as:Public",
        "Public",
    ];
    if audience.iter().any(|item| PUBLIC_VARIANTS.contains(&item.as_str())) {
       return Visibility::Public;
    };
    let actor = author.actor_json.as_ref()
        .expect("actor data should be present");
    if let Some(ref followers) = actor.followers {
        if audience.contains(followers) {
            return Visibility::Followers;
        };
    };
    if let Some(ref subscribers) = actor.subscribers {
        if audience.contains(subscribers) {
            return Visibility::Subscribers;
        };
    };
    Visibility::Direct
}

pub async fn handle_note(
    config: &Config,
    db_client: &mut impl DatabaseClient,
    object: Object,
    redirects: &HashMap<String, String>,
) -> Result<Post, HandlerError> {
    let instance = config.instance();
    let media_dir = config.media_dir();
    match object.object_type.as_str() {
        NOTE => (),
        ARTICLE | EVENT | QUESTION | PAGE | VIDEO => {
            log::info!("processing object of type {}", object.object_type);
        },
        other_type => {
            log::warn!("discarding object of type {}", other_type);
            return Err(ValidationError("unsupported object type").into());
        },
    };

    let author_id = get_object_attributed_to(&object)?;
    let author = get_or_import_profile_by_actor_id(
        db_client,
        &instance,
        &media_dir,
        &author_id,
    ).await.map_err(|err| {
        log::warn!("failed to import {} ({})", author_id, err);
        err
    })?;

    let mut content = get_object_content(&object)?;
    if object.object_type != NOTE {
        // Append link to object
        let object_url = get_object_url(&object)?;
        content += &create_content_link(object_url);
    };
    let (attachments, unprocessed) = get_object_attachments(
        config,
        db_client,
        &object,
        &author,
    ).await?;
    for attachment_url in unprocessed {
        content += &create_content_link(attachment_url);
    };
    if content.is_empty() && attachments.is_empty() {
        return Err(ValidationError("post is empty").into());
    };

    let (mentions, hashtags, links, emojis) = get_object_tags(
        config,
        db_client,
        &object,
        redirects,
    ).await?;

    let in_reply_to_id = match object.in_reply_to {
        Some(ref object_id) => {
            let object_id = redirects.get(object_id).unwrap_or(object_id);
            let in_reply_to = get_post_by_object_id(
                db_client,
                &instance.url(),
                object_id,
            ).await?;
            Some(in_reply_to.id)
        },
        None => None,
    };
    let primary_audience = match object.to {
        Some(value) => {
            parse_array(&value)
                .map_err(|_| ValidationError("invalid 'to' property value"))?
        },
        None => vec![],
    };
    let secondary_audience = match object.cc {
        Some(value) => {
            parse_array(&value)
                .map_err(|_| ValidationError("invalid 'cc' property value"))?
        },
        None => vec![],
    };
    let visibility = get_object_visibility(
        &author,
        primary_audience,
        secondary_audience,
    );
    if visibility != Visibility::Public {
        log::warn!(
            "processing note with visibility {:?} attributed to {}",
            visibility,
            author.username,
        );
    };
    let created_at = object.published.unwrap_or(Utc::now());
    let post_data = PostCreateData {
        content: content,
        in_reply_to_id,
        repost_of_id: None,
        visibility,
        attachments: attachments,
        mentions: mentions,
        tags: hashtags,
        links: links,
        emojis: emojis,
        object_id: Some(object.id),
        created_at,
    };
    let post = create_post(db_client, &author.id, post_data).await?;
    Ok(post)
}

pub async fn handle_create(
    config: &Config,
    db_client: &mut impl DatabaseClient,
    activity: JsonValue,
    is_authenticated: bool,
) -> HandlerResult {
    let object: Object = serde_json::from_value(activity["object"].to_owned())
        .map_err(|_| ValidationError("invalid object"))?;
    let object_id = object.id.clone();
    let object_received = if is_authenticated {
        Some(object)
    } else {
        // Fetch object, don't trust the sender.
        // Most likely it's a forwarded reply.
        None
    };
    import_post(config, db_client, object_id, object_received).await?;
    Ok(Some(NOTE))
}

#[cfg(test)]
mod tests {
    use serde_json::json;
    use crate::activitypub::{
        actors::types::Actor,
        types::Object,
        vocabulary::NOTE,
    };
    use super::*;

    #[test]
    fn test_get_object_attributed_to() {
       let object = Object {
            object_type: NOTE.to_string(),
            attributed_to: Some(json!(["https://example.org/1"])),
            ..Default::default()
        };
        let author_id = get_object_attributed_to(&object).unwrap();
        assert_eq!(author_id, "https://example.org/1");
    }

    #[test]
    fn test_get_object_content() {
        let object = Object {
            content: Some("test".to_string()),
            object_type: NOTE.to_string(),
            ..Default::default()
        };
        let content = get_object_content(&object).unwrap();
        assert_eq!(content, "test");
    }

    #[test]
    fn test_get_object_content_from_video() {
        let object = Object {
            name: Some("test-name".to_string()),
            content: Some("test-content".to_string()),
            object_type: "Video".to_string(),
            url: Some(json!([{
                "type": "Link",
                "mediaType": "text/html",
                "href": "https://example.org/xyz",
            }])),
            ..Default::default()
        };
        let mut content = get_object_content(&object).unwrap();
        let object_url = get_object_url(&object).unwrap();
        content += &create_content_link(object_url);
        assert_eq!(
            content,
            r#"test-content<p><a href="https://example.org/xyz" rel="noopener">https://example.org/xyz</a></p>"#,
        );
    }

    #[test]
    fn test_get_object_visibility_public() {
        let author = DbActorProfile::default();
        let primary_audience = vec![AP_PUBLIC.to_string()];
        let secondary_audience = vec![];
        let visibility = get_object_visibility(
            &author,
            primary_audience,
            secondary_audience,
        );
        assert_eq!(visibility, Visibility::Public);
    }

    #[test]
    fn test_get_object_visibility_followers() {
        let author_followers = "https://example.com/users/author/followers";
        let author = DbActorProfile {
            actor_json: Some(Actor {
                followers: Some(author_followers.to_string()),
                ..Default::default()
            }),
            ..Default::default()
        };
        let primary_audience = vec![author_followers.to_string()];
        let secondary_audience = vec![];
        let visibility = get_object_visibility(
            &author,
            primary_audience,
            secondary_audience,
        );
        assert_eq!(visibility, Visibility::Followers);
    }

    #[test]
    fn test_get_object_visibility_subscribers() {
        let author_followers = "https://example.com/users/author/followers";
        let author_subscribers = "https://example.com/users/author/subscribers";
        let author = DbActorProfile {
            actor_json: Some(Actor {
                followers: Some(author_followers.to_string()),
                subscribers: Some(author_subscribers.to_string()),
                ..Default::default()
            }),
            ..Default::default()
        };
        let primary_audience = vec![author_subscribers.to_string()];
        let secondary_audience = vec![];
        let visibility = get_object_visibility(
            &author,
            primary_audience,
            secondary_audience,
        );
        assert_eq!(visibility, Visibility::Subscribers);
    }

    #[test]
    fn test_get_object_visibility_direct() {
        let author = DbActorProfile {
            actor_json: Some(Actor::default()),
            ..Default::default()
        };
        let primary_audience = vec!["https://example.com/users/1".to_string()];
        let secondary_audience = vec![];
        let visibility = get_object_visibility(
            &author,
            primary_audience,
            secondary_audience,
        );
        assert_eq!(visibility, Visibility::Direct);
    }
}