use db::database::AppDatabase;
use serde::Deserialize;
use sha2::{Digest, Sha256};
use std::time::Duration;
use tokio::time::timeout;

/// Compute HMAC-SHA256 of `body` with `secret`, returning "sha256=<hex>" or None if secret is empty.
pub fn sign_payload(body: &[u8], secret: &str) -> Option<String> {
    if secret.is_empty() {
        return None;
    }

    // HMAC-SHA256: inner = SHA256(k XOR ipad || text), outer = SHA256(k XOR opad || inner)
    const IPAD: u8 = 0x36;
    const OPAD: u8 = 0x5c;
    const BLOCK_SIZE: usize = 64; // SHA256 block size

    // Pad or hash key to 64 bytes
    let key = if secret.len() > BLOCK_SIZE {
        Sha256::digest(secret.as_bytes()).to_vec()
    } else {
        secret.as_bytes().to_vec()
    };
    let mut key_block = vec![0u8; BLOCK_SIZE];
    key_block[..key.len()].copy_from_slice(&key);

    // k_ipad = key_block XOR ipad, k_opad = key_block XOR opad
    let mut k_ipad = [0u8; BLOCK_SIZE];
    let mut k_opad = [0u8; BLOCK_SIZE];
    for i in 0..BLOCK_SIZE {
        k_ipad[i] = key_block[i] ^ IPAD;
        k_opad[i] = key_block[i] ^ OPAD;
    }

    // inner = SHA256(k_ipad || body)
    let mut inner_hasher = Sha256::new();
    inner_hasher.update(&k_ipad);
    inner_hasher.update(body);
    let inner = inner_hasher.finalize();

    // outer = SHA256(k_opad || inner)
    let mut outer_hasher = Sha256::new();
    outer_hasher.update(&k_opad);
    outer_hasher.update(inner);
    let result = outer_hasher.finalize();

    Some(format!(
        "sha256={}",
        result
            .iter()
            .map(|b| format!("{:02x}", b))
            .collect::<String>()
    ))
}

#[derive(Debug, Clone, Default, Deserialize)]
pub struct WebhookEvents {
    pub push: bool,
    pub tag_push: bool,
    pub pull_request: bool,
    pub issue_comment: bool,
    pub release: bool,
}

impl From<serde_json::Value> for WebhookEvents {
    fn from(v: serde_json::Value) -> Self {
        Self {
            push: v.get("push").and_then(|v| v.as_bool()).unwrap_or(false),
            tag_push: v.get("tag_push").and_then(|v| v.as_bool()).unwrap_or(false),
            pull_request: v
                .get("pull_request")
                .and_then(|v| v.as_bool())
                .unwrap_or(false),
            issue_comment: v
                .get("issue_comment")
                .and_then(|v| v.as_bool())
                .unwrap_or(false),
            release: v.get("release").and_then(|v| v.as_bool()).unwrap_or(false),
        }
    }
}

#[derive(Debug, serde::Serialize)]
pub struct PushPayload {
    #[serde(rename = "ref")]
    pub r#ref: String,
    pub before: String,
    pub after: String,
    pub repository: RepositoryPayload,
    pub pusher: PusherPayload,
    #[serde(skip_serializing_if = "Vec::is_empty")]
    pub commits: Vec<CommitPayload>,
}

#[derive(Debug, serde::Serialize)]
pub struct TagPushPayload {
    #[serde(rename = "ref")]
    pub r#ref: String,
    pub before: String,
    pub after: String,
    pub repository: RepositoryPayload,
    pub pusher: PusherPayload,
}

#[derive(Debug, serde::Serialize)]
pub struct RepositoryPayload {
    pub id: String,
    pub name: String,
    pub full_name: String,
    pub namespace: String,
    pub default_branch: String,
}

#[derive(Debug, serde::Serialize)]
pub struct PusherPayload {
    pub name: String,
    pub email: String,
}

#[derive(Debug, serde::Serialize)]
pub struct CommitPayload {
    pub id: String,
    pub message: String,
    pub author: AuthorPayload,
}

#[derive(Debug, serde::Serialize)]
pub struct AuthorPayload {
    pub name: String,
    pub email: String,
}

#[derive(Debug)]
pub enum DispatchError {
    Timeout,
    ConnectionFailed,
    RequestFailed(String),
    HttpError(u16),
}

impl std::fmt::Display for DispatchError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            DispatchError::Timeout => write!(f, "timeout"),
            DispatchError::ConnectionFailed => write!(f, "connection failed"),
            DispatchError::RequestFailed(s) => write!(f, "request failed: {}", s),
            DispatchError::HttpError(code) => write!(f, "http error: {}", code),
        }
    }
}

pub async fn deliver(
    client: &reqwest::Client,
    url: &str,
    secret: Option<&str>,
    content_type: &str,
    body: &[u8],
) -> Result<(), DispatchError> {
    let mut req = client
        .post(url)
        .header("Content-Type", content_type)
        .header("User-Agent", "Code-Git-Hook/1.0")
        .timeout(Duration::from_secs(10))
        .body(body.to_vec());

    if let Some(secret) = secret {
        if let Some(sig) = sign_payload(body, secret) {
            req = req.header("X-Hub-Signature-256", sig);
        }
    }

    let resp = req.send().await.map_err(|e| {
        if e.is_timeout() {
            DispatchError::Timeout
        } else if e.is_connect() {
            DispatchError::ConnectionFailed
        } else {
            DispatchError::RequestFailed(e.to_string())
        }
    })?;

    if resp.status().is_success() {
        Ok(())
    } else {
        Err(DispatchError::HttpError(resp.status().as_u16()))
    }
}

pub struct CommitDispatch {
    pub id: String,
    pub message: String,
    pub author_name: String,
    pub author_email: String,
}

pub enum WebhookEventKind {
    Push {
        r#ref: String,
        before: String,
        after: String,
        commits: Vec<CommitDispatch>,
    },
    TagPush {
        r#ref: String,
        before: String,
        after: String,
    },
}

/// Dispatch webhooks for a repository after a push or tag event.
/// Queries active webhooks from the DB and sends HTTP POST requests.
pub async fn dispatch_repo_webhooks(
    db: &AppDatabase,
    http: &reqwest::Client,
    logs: &slog::Logger,
    repo_uuid: &str,
    namespace: &str,
    repo_name: &str,
    default_branch: &str,
    pusher_name: &str,
    pusher_email: &str,
    event: WebhookEventKind,
) {
    use models::repos::repo_webhook::{Column as RwCol, Entity as RepoWebhookEntity};
    use models::{ColumnTrait, EntityTrait, QueryFilter, Uuid};

    let webhooks: Vec<<RepoWebhookEntity as EntityTrait>::Model> = match RepoWebhookEntity::find()
        .filter(RwCol::Repo.eq(Uuid::parse_str(repo_uuid).ok()))
        .all(db.reader())
        .await
    {
        Ok(ws) => ws,
        Err(e) => {
            slog::error!(logs, "failed to query webhooks: {}", e; "repo" => repo_uuid);
            return;
        }
    };

    if webhooks.is_empty() {
        return;
    }

    for webhook in webhooks {
        let event_config: WebhookEvents =
            serde_json::from_value(webhook.event.clone()).unwrap_or_default();
        let content_type = webhook
            .event
            .get("content_type")
            .and_then(|v: &serde_json::Value| v.as_str())
            .unwrap_or("application/json");
        let url = webhook.url.as_deref().unwrap_or("");

        if url.is_empty() {
            continue;
        }

        let secret = webhook.secret_key.as_deref();

        match &event {
            WebhookEventKind::Push {
                r#ref,
                before,
                after,
                commits,
            } => {
                if !event_config.push {
                    continue;
                }
                let payload = PushPayload {
                    r#ref: r#ref.clone(),
                    before: before.clone(),
                    after: after.clone(),
                    repository: RepositoryPayload {
                        id: repo_uuid.to_owned(),
                        name: repo_name.to_owned(),
                        full_name: format!("{}/{}", namespace, repo_name),
                        namespace: namespace.to_owned(),
                        default_branch: default_branch.to_owned(),
                    },
                    pusher: PusherPayload {
                        name: pusher_name.to_owned(),
                        email: pusher_email.to_owned(),
                    },
                    commits: commits
                        .iter()
                        .map(|c| CommitPayload {
                            id: c.id.clone(),
                            message: c.message.clone(),
                            author: AuthorPayload {
                                name: c.author_name.clone(),
                                email: c.author_email.clone(),
                            },
                        })
                        .collect(),
                };

                let body = match serde_json::to_vec(&payload) {
                    Ok(b) => b,
                    Err(e) => {
                        slog::error!(logs, "failed to serialize push payload"; "error" => e.to_string());
                        continue;
                    }
                };

                let webhook_id = webhook.id;
                match timeout(
                    Duration::from_secs(10),
                    deliver(http, url, secret, content_type, &body),
                )
                .await
                {
                    Ok(Ok(())) => {
                        slog::info!(logs, "push webhook delivered"; "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, true, logs).await;
                    }
                    Ok(Err(e)) => {
                        slog::warn!(logs, "push webhook delivery failed"; "error" => e.to_string(), "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, false, logs).await;
                    }
                    Err(_) => {
                        slog::warn!(logs, "push webhook timed out"; "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, false, logs).await;
                    }
                }
            }
            WebhookEventKind::TagPush {
                r#ref,
                before,
                after,
            } => {
                if !event_config.tag_push {
                    continue;
                }
                let payload = TagPushPayload {
                    r#ref: r#ref.clone(),
                    before: before.clone(),
                    after: after.clone(),
                    repository: RepositoryPayload {
                        id: repo_uuid.to_owned(),
                        name: repo_name.to_owned(),
                        full_name: format!("{}/{}", namespace, repo_name),
                        namespace: namespace.to_owned(),
                        default_branch: default_branch.to_owned(),
                    },
                    pusher: PusherPayload {
                        name: pusher_name.to_owned(),
                        email: pusher_email.to_owned(),
                    },
                };

                let body = match serde_json::to_vec(&payload) {
                    Ok(b) => b,
                    Err(e) => {
                        slog::error!(logs, "failed to serialize tag payload"; "error" => e.to_string());
                        continue;
                    }
                };

                let webhook_id = webhook.id;
                match timeout(
                    Duration::from_secs(10),
                    deliver(http, url, secret, content_type, &body),
                )
                .await
                {
                    Ok(Ok(())) => {
                        slog::info!(logs, "tag webhook delivered"; "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, true, logs).await;
                    }
                    Ok(Err(e)) => {
                        slog::warn!(logs, "tag webhook delivery failed"; "error" => e.to_string(), "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, false, logs).await;
                    }
                    Err(_) => {
                        slog::warn!(logs, "tag webhook timed out"; "webhook_id" => webhook_id, "url" => url);
                        let _ = touch_webhook(db, webhook_id, false, logs).await;
                    }
                }
            }
        }
    }
}

async fn touch_webhook(db: &AppDatabase, webhook_id: i64, success: bool, logs: &slog::Logger) {
    use models::repos::repo_webhook::{Column as RwCol, Entity as RepoWebhookEntity};
    use models::{ColumnTrait, EntityTrait, QueryFilter};
    use sea_orm::prelude::Expr;

    let result: Result<sea_orm::UpdateResult, sea_orm::DbErr> = if success {
        RepoWebhookEntity::update_many()
            .filter(RwCol::Id.eq(webhook_id))
            .col_expr(
                RwCol::LastDeliveredAt,
                Expr::value(Some(chrono::Utc::now())),
            )
            .col_expr(RwCol::TouchCount, Expr::value(1i64))
            .exec(db.writer())
            .await
    } else {
        RepoWebhookEntity::update_many()
            .filter(RwCol::Id.eq(webhook_id))
            .col_expr(RwCol::TouchCount, Expr::value(1i64))
            .exec(db.writer())
            .await
    };

    if let Err(e) = result {
        slog::warn!(logs, "failed to update webhook touch"; "error" => e.to_string());
    }
}