use actix::prelude::*;
use git_next_config::{
    server::{Webhook, WebhookUrl},
    BranchName, ForgeAlias, RepoAlias, RepoBranches,
};
use git_next_git as git;
use kxio::network::{self, json};
use tracing::{info, warn};
use ulid::DecodeError;

use std::{collections::HashMap, str::FromStr};

use crate::{RepoActor, ValidateRepo, WebhookRegistered};

#[derive(
    Clone, Debug, PartialEq, Eq, derive_more::Constructor, derive_more::Deref, derive_more::Display,
)]
pub struct WebhookId(String);

#[derive(Clone, Debug, PartialEq, Eq, derive_more::Deref, derive_more::Display)]
pub struct WebhookAuth(ulid::Ulid);
impl WebhookAuth {
    pub fn new(authorisation: &str) -> Result<Self, DecodeError> {
        let id = ulid::Ulid::from_str(authorisation)?;
        info!("Parse auth token: {}", id);
        Ok(Self(id))
    }

    fn generate() -> Self {
        Self(ulid::Ulid::new())
    }

    fn header_value(&self) -> String {
        format!("Basic {}", self)
    }
}

#[tracing::instrument(skip_all, fields(%webhook_id))]
pub async fn unregister(
    webhook_id: WebhookId,
    repo_details: git::RepoDetails,
    net: network::Network,
) {
    let hostname = &repo_details.forge.hostname();
    let repo_path = repo_details.repo_path;
    use secrecy::ExposeSecret;
    let token = repo_details.forge.token().expose_secret();
    let url = network::NetUrl::new(format!(
        "https://{hostname}/api/v1/repos/{repo_path}/hooks/{webhook_id}?token={token}"
    ));
    let request = network::NetRequest::new(
        network::RequestMethod::Delete,
        url,
        network::NetRequestHeaders::new(),
        network::RequestBody::None,
        network::ResponseType::None,
        None,
        network::NetRequestLogging::None,
    );
    let result = net.delete(request).await;
    match result {
        Ok(_) => info!("unregistered webhook"),
        Err(err) => warn!(?err, "Failed to unregister webhook"),
    }
}

#[tracing::instrument(skip_all)]
pub async fn register(
    repo_details: git::RepoDetails,
    webhook: Webhook,
    addr: actix::prelude::Addr<super::RepoActor>,
    net: network::Network,
) {
    let Some(repo_config) = repo_details.repo_config.clone() else {
        return;
    };

    let forge_alias = repo_details.forge.forge_alias();
    let repo_alias = &repo_details.repo_alias;
    let webhook_url = webhook.url(forge_alias, repo_alias);
    // remove any lingering webhooks for the same URL
    let existing_webhook_ids = find_existing_webhooks(&repo_details, &webhook_url, &net).await;
    for webhook_id in existing_webhook_ids {
        unregister(webhook_id, repo_details.clone(), net.clone()).await;
    }

    let hostname = &repo_details.forge.hostname();
    let repo_path = repo_details.repo_path;
    use secrecy::ExposeSecret;
    let token = repo_details.forge.token().expose_secret();
    let url = network::NetUrl::new(format!(
        "https://{hostname}/api/v1/repos/{repo_path}/hooks?token={token}"
    ));
    let headers = network::NetRequestHeaders::new().with("Content-Type", "application/json");
    let authorisation = WebhookAuth::generate();
    let body = json!({
      "active": true,
      "authorization_header": authorisation.header_value(),
      "branch_filter": format!("{{{},{},{}}}", repo_config.branches().main(), repo_config.branches().next(), repo_config.branches().dev()),
      "config": {
        "content_type": "json",
        "url": webhook_url.as_ref(),
      },
      "events": [ "push" ],
      "type": "forgejo"
    });
    let request = network::NetRequest::new(
        network::RequestMethod::Post,
        url,
        headers,
        network::RequestBody::Json(body),
        network::ResponseType::Json,
        None,
        network::NetRequestLogging::None,
    );
    let result = net.post_json::<Hook>(request).await;
    match result {
        Ok(response) => {
            if let Some(hook) = response.response_body() {
                info!(webhook_id = %hook.id, "Webhook registered");
                addr.do_send(WebhookRegistered(hook.id(), authorisation));
            }
        }
        Err(_) => warn!("Failed to register webhook"),
    }
}

async fn find_existing_webhooks(
    repo_details: &git::RepoDetails,
    webhook_url: &WebhookUrl,
    net: &network::Network,
) -> Vec<WebhookId> {
    let mut ids: Vec<WebhookId> = vec![];
    let hostname = &repo_details.forge.hostname();
    let repo_path = &repo_details.repo_path;
    let mut page = 1;
    loop {
        use secrecy::ExposeSecret;
        let token = &repo_details.forge.token().expose_secret();
        let url =
            format!("https://{hostname}/api/v1/repos/{repo_path}/hooks?page={page}&token={token}");
        let net_url = network::NetUrl::new(url);
        let request = network::NetRequest::new(
            network::RequestMethod::Get,
            net_url,
            network::NetRequestHeaders::new(),
            network::RequestBody::None,
            network::ResponseType::Json,
            None,
            network::NetRequestLogging::None,
        );
        let result = net.get::<Vec<Hook>>(request).await;
        if let Ok(response) = result {
            if let Some(list) = response.response_body() {
                if list.is_empty() {
                    return ids;
                }
                for hook in list {
                    if let Some(existing_url) = hook.config.get("url") {
                        if existing_url == webhook_url.as_ref() {
                            ids.push(hook.id());
                        }
                    }
                }
            }
        }
        page += 1;
    }
}

#[derive(Debug, serde::Deserialize)]
struct Hook {
    id: i64,
    config: HashMap<String, String>,
}
impl Hook {
    fn id(&self) -> WebhookId {
        WebhookId(format!("{}", self.id))
    }
}

impl Handler<WebhookMessage> for RepoActor {
    type Result = ();

    #[allow(clippy::cognitive_complexity)] // TODO: (#49) reduce complexity
    #[tracing::instrument(name = "RepoActor::WebhookMessage", skip_all, fields(token = %self.message_token, repo = %self.repo_details))]
    fn handle(&mut self, msg: WebhookMessage, ctx: &mut Self::Context) -> Self::Result {
        let Some(expected_authorization) = &self.webhook_auth else {
            warn!("Don't know what authorization to expect");
            return;
        };
        if msg.authorisation() != expected_authorization {
            warn!(
                "Invalid authorization - expected {}",
                expected_authorization
            );
            return;
        }
        let body = msg.body();
        match serde_json::from_str::<Push>(body.as_str()) {
            Err(err) => warn!(?err, ?body, "Not a 'push'"),
            Ok(push) => {
                if let Some(config) = &self.repo_details.repo_config {
                    match push.branch(config.branches()) {
                        None => warn!(
                            ?push,
                            "Unrecognised branch, we should be filtering to only the ones we want"
                        ),
                        Some(branch) => {
                            match branch {
                                Branch::Main => {
                                    if self.last_main_commit == Some(push.commit()) {
                                        info!(
                                            branch = %config.branches().main(),
                                            commit = %push.commit(),
                                            "Ignoring - already aware of branch at commit",
                                        );
                                        return;
                                    }
                                    self.last_main_commit.replace(push.commit())
                                }
                                Branch::Next => {
                                    if self.last_next_commit == Some(push.commit()) {
                                        info!(
                                            branch = %config.branches().next(),
                                            commit = %push.commit(),
                                            "Ignoring - already aware of branch at commit",
                                        );
                                        return;
                                    }
                                    self.last_next_commit.replace(push.commit())
                                }
                                Branch::Dev => {
                                    if self.last_dev_commit == Some(push.commit()) {
                                        info!(
                                            branch = %config.branches().dev(),
                                            commit = %push.commit(),
                                            "Ignoring - already aware of branch at commit",
                                        );
                                        return;
                                    }
                                    self.last_dev_commit.replace(push.commit())
                                }
                            };
                            let message_token = self.message_token.next();
                            info!(
                                token = %message_token,
                                ?branch,
                                commit = %push.commit(),
                                "New commit"
                            );
                            ctx.address().do_send(ValidateRepo { message_token });
                        }
                    }
                }
            }
        }
    }
}

pub fn split_ref(reference: &str) -> (&str, &str) {
    reference.split_at(11)
}

#[derive(Debug, serde::Deserialize)]
struct Push {
    #[serde(rename = "ref")]
    reference: String,
    after: String,
    head_commit: HeadCommit,
}
impl Push {
    pub fn branch(&self, repo_branches: &RepoBranches) -> Option<Branch> {
        if !self.reference.starts_with("refs/heads/") {
            warn!(r#ref = self.reference, "Unexpected ref");
            return None;
        }
        let (_, branch) = split_ref(&self.reference);
        let branch = BranchName::new(branch);
        if branch == repo_branches.main() {
            return Some(Branch::Main);
        }
        if branch == repo_branches.next() {
            return Some(Branch::Next);
        }
        if branch == repo_branches.dev() {
            return Some(Branch::Dev);
        }
        warn!(%branch, "Unexpected branch");
        None
    }

    pub fn commit(&self) -> git::Commit {
        git::Commit::new(
            git::commit::Sha::new(self.after.clone()),
            git::commit::Message::new(self.head_commit.message.clone()),
        )
    }
}

#[derive(Debug)]
pub enum Branch {
    Main,
    Next,
    Dev,
}

#[derive(Debug, serde::Deserialize)]
struct HeadCommit {
    message: String,
}

#[derive(Message, Debug, Clone, derive_more::Constructor)]
#[rtype(result = "()")]
pub struct WebhookMessage {
    forge_alias: ForgeAlias,
    repo_alias: RepoAlias,
    authorisation: WebhookAuth,
    body: Body,
}
impl WebhookMessage {
    pub const fn forge_alias(&self) -> &ForgeAlias {
        &self.forge_alias
    }
    pub const fn repo_alias(&self) -> &RepoAlias {
        &self.repo_alias
    }
    pub const fn body(&self) -> &Body {
        &self.body
    }
    pub const fn authorisation(&self) -> &WebhookAuth {
        &self.authorisation
    }
}

#[derive(Clone, Debug, derive_more::Constructor)]
pub struct Body(String);
impl Body {
    pub fn as_str(&self) -> &str {
        self.0.as_str()
    }
}