use std::collections::HashMap;
use std::fs::File;
use std::io::Read;

use anyhow::{anyhow, bail, Result};
use bytes::Bytes;
use log::*;
use reqwest::StatusCode;
use serde::{Deserialize, Serialize};

pub struct ConsulConfig {
	pub addr: String,
	pub ca_cert: Option<String>,
	pub tls_skip_verify: bool,
	pub client_cert: Option<String>,
	pub client_key: Option<String>,
}

// ---- Watch and retrieve Consul catalog ----
//
#[derive(Serialize, Deserialize, Debug)]
pub struct ConsulNode {
	#[serde(rename = "Node")]
	pub node: String,
	#[serde(rename = "Address")]
	pub address: String,
	#[serde(rename = "Meta")]
	pub meta: HashMap<String, String>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct ConsulServiceEntry {
	#[serde(rename = "Service")]
	pub service: String,

	#[serde(rename = "Address")]
	pub address: String,

	#[serde(rename = "Port")]
	pub port: u16,

	#[serde(rename = "Tags")]
	pub tags: Vec<String>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct ConsulNodeCatalog {
	#[serde(rename = "Node")]
	pub node: ConsulNode,
	#[serde(rename = "Services")]
	pub services: HashMap<String, ConsulServiceEntry>,
}

// ---- Consul session management ----

#[derive(Serialize, Deserialize, Debug)]
pub struct ConsulSessionRequest {
	#[serde(rename = "Name")]
	pub name: String,

	#[serde(rename = "Node")]
	pub node: Option<String>,

	#[serde(rename = "LockDelay")]
	pub lock_delay: Option<String>,

	#[serde(rename = "TTL")]
	pub ttl: Option<String>,

	#[serde(rename = "Behavior")]
	pub behavior: Option<String>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct ConsulSessionResponse {
	#[serde(rename = "ID")]
	pub id: String,
}

#[derive(Clone)]
pub struct Consul {
	client: reqwest::Client,

	url: String,
	kv_prefix: String,
}

impl Consul {
	pub fn new(config: ConsulConfig, kv_prefix: &str) -> Result<Self> {
		let client = match (&config.client_cert, &config.client_key) {
			(Some(client_cert), Some(client_key)) => {
				let mut client_cert_buf = vec![];
				File::open(client_cert)?.read_to_end(&mut client_cert_buf)?;

				let mut client_key_buf = vec![];
				File::open(client_key)?.read_to_end(&mut client_key_buf)?;

				let identity = reqwest::Identity::from_pem(
					&[&client_cert_buf[..], &client_key_buf[..]].concat()[..],
				)?;

				if config.tls_skip_verify {
					reqwest::Client::builder()
						.use_rustls_tls()
						.danger_accept_invalid_certs(true)
						.identity(identity)
						.build()?
				} else if let Some(ca_cert) = &config.ca_cert {
					let mut ca_cert_buf = vec![];
					File::open(ca_cert)?.read_to_end(&mut ca_cert_buf)?;

					reqwest::Client::builder()
						.use_rustls_tls()
						.add_root_certificate(reqwest::Certificate::from_pem(&ca_cert_buf[..])?)
						.identity(identity)
						.build()?
				} else {
					reqwest::Client::builder()
						.use_rustls_tls()
						.identity(identity)
						.build()?
				}
			}
			(None, None) => reqwest::Client::new(),
			_ => bail!("Incomplete Consul TLS configuration parameters"),
		};

		Ok(Self {
			client,
			url: config.addr.trim_end_matches('/').to_string(),
			kv_prefix: kv_prefix.to_string(),
		})
	}

	pub async fn list_nodes(&self) -> Result<Vec<ConsulNode>> {
		debug!("list_nodes");

		let url = format!("{}/v1/catalog/nodes", self.url);

		let http = self.client.get(&url).send().await?;
		let resp: Vec<ConsulNode> = http.json().await?;
		Ok(resp)
	}

	pub async fn watch_node(
		&self,
		host: &str,
		idx: Option<usize>,
	) -> Result<(Option<ConsulNodeCatalog>, usize)> {
		debug!("watch_node {} {:?}", host, idx);

		let url = match idx {
			Some(i) => format!("{}/v1/catalog/node/{}?index={}", self.url, host, i),
			None => format!("{}/v1/catalog/node/{}", self.url, host),
		};

		let http = self.client.get(&url).send().await?;
		let new_idx = match http.headers().get("X-Consul-Index") {
			Some(v) => v.to_str()?.parse::<usize>()?,
			None => bail!("X-Consul-Index header not found"),
		};

		let resp: Option<ConsulNodeCatalog> = http.json().await?;
		Ok((resp, new_idx))
	}

	// ---- KV get and put ----

	pub async fn kv_get(&self, key: &str) -> Result<Option<Bytes>> {
		debug!("kv_get {}", key);

		let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
		let http = self.client.get(&url).send().await?;
		match http.status() {
			StatusCode::OK => Ok(Some(http.bytes().await?)),
			StatusCode::NOT_FOUND => Ok(None),
			_ => Err(anyhow!(
				"Consul request failed: {:?}",
				http.error_for_status()
			)),
		}
	}

	pub async fn kv_get_json<T: for<'de> Deserialize<'de>>(&self, key: &str) -> Result<Option<T>> {
		debug!("kv_get_json {}", key);

		let url = format!("{}/v1/kv/{}{}?raw", self.url, self.kv_prefix, key);
		let http = self.client.get(&url).send().await?;
		match http.status() {
			StatusCode::OK => Ok(Some(http.json().await?)),
			StatusCode::NOT_FOUND => Ok(None),
			_ => Err(anyhow!(
				"Consul request failed: {:?}",
				http.error_for_status()
			)),
		}
	}

	pub async fn kv_put(&self, key: &str, bytes: Bytes) -> Result<()> {
		debug!("kv_put {}", key);

		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
		let http = self.client.put(&url).body(bytes).send().await?;
		http.error_for_status()?;
		Ok(())
	}

	pub async fn kv_put_json<T: Serialize>(&self, key: &str, value: &T) -> Result<()> {
		debug!("kv_put_json {}", key);

		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
		let http = self.client.put(&url).json(value).send().await?;
		http.error_for_status()?;
		Ok(())
	}

	pub async fn kv_delete(&self, key: &str) -> Result<()> {
		let url = format!("{}/v1/kv/{}{}", self.url, self.kv_prefix, key);
		let http = self.client.delete(&url).send().await?;
		http.error_for_status()?;
		Ok(())
	}

	// ---- Locking ----

	pub async fn create_session(&self, req: &ConsulSessionRequest) -> Result<String> {
		debug!("create_session {:?}", req);

		let url = format!("{}/v1/session/create", self.url);
		let http = self.client.put(&url).json(req).send().await?;
		let resp: ConsulSessionResponse = http.json().await?;
		Ok(resp.id)
	}

	pub async fn acquire(&self, key: &str, bytes: Bytes, session: &str) -> Result<bool> {
		debug!("acquire {}", key);

		let url = format!(
			"{}/v1/kv/{}{}?acquire={}",
			self.url, self.kv_prefix, key, session
		);
		let http = self.client.put(&url).body(bytes).send().await?;
		let resp: bool = http.json().await?;
		Ok(resp)
	}

	pub async fn release(&self, key: &str, bytes: Bytes, session: &str) -> Result<()> {
		debug!("release {}", key);

		let url = format!(
			"{}/v1/kv/{}{}?release={}",
			self.url, self.kv_prefix, key, session
		);
		let http = self.client.put(&url).body(bytes).send().await?;
		http.error_for_status()?;
		Ok(())
	}
}