use anyhow::Result;
use chrono::{DateTime, Local};
use log::*;
use serde::{Deserialize, Serialize};
use std::{
	collections::{HashMap, HashSet},
	fs::{self, File},
	io::{Read, Write},
	path::{Path, PathBuf},
};

use crate::{endpoint::Endpoint, Registry};

/// Local user data collected from the various regitries.
///
/// It contains the list of registries. Some may be disabled.
/// The data for each registry can be updated in order to keep
/// a fresh list of endpoints.
#[derive(PartialEq, Debug, Deserialize, Serialize)]
pub struct LocalData {
	/// File where the local data are stored
	pub file: PathBuf,

	/// List of the registries where the RPC endpoints are pulled from
	pub registries: HashMap<String, Registry>,

	/// DateTime of the last update of the data
	pub last_update: Option<DateTime<Local>>,
}

impl LocalData {
	pub fn get_default_file() -> PathBuf {
		let home = dirs::home_dir().expect("Failed fetching home dir");
		let dir = Path::new(&home).join(".subrpc");
		let _ = fs::create_dir_all(&dir);
		dir.join("data.json")
	}

	/// Returns true if the local file exists
	pub fn initialized(&self) -> bool {
		self.file.exists()
	}

	/// Initialize a DB based on a given file.
	/// After initializing a DB, you should ensure it contains
	/// at least one registry and call the [Self::refresh] function.
	pub fn init(file: &Path, force: bool) -> Result<Self> {
		debug!("Initializing local data in {} with force: {:?}", file.display(), force);

		let data = Self { file: file.to_path_buf(), ..Default::default() };

		if file.exists() && !force {
			info!("File already exists: {}", file.display());
			data.load()
		} else {
			data.save()
		}
	}

	/// Load [LocalData] and deserialize data from [file].
	pub fn load(self) -> Result<Self> {
		debug!("Loading data from {}", self.file.display());
		let mut fs = File::open(self.file)?;
		let mut s = String::new();
		fs.read_to_string(&mut s)?;
		serde_json::from_str(&s).map_err(anyhow::Error::msg)
	}

	/// Loops through each registry, each network/chain, each endpoint
	/// and update the endpoints lists.
	pub fn refresh(mut self) -> Self {
		debug!("Refreshing registries");

		self.registries.iter_mut().for_each(|(_registry_name, reg)| {
			debug!(" - {} - enabled: {:?}", &reg.name, &reg.enabled);
			// println!("reg = {:?}", &reg);
			match reg.update() {
				Ok(_) => {
					info!("Update of '{}' OK", reg.name);
				}
				Err(e) => {
					// eprintln!("{e:?}");
					error!("Update registry '{}' failed: {e:?}", reg.name);
				}
			}
		});

		self.last_update = Some(Local::now());
		self
	}

	/// Add a new registry. Registries are identitfied by their names, make sure the name is unique.
	pub fn add_registry(mut self, registry: Registry) -> Self {
		self.registries.insert(registry.name.clone(), registry);
		self
	}

	/// Save the current state to file
	pub fn save(self) -> Result<Self> {
		debug!("Saving data to {}", self.file.display());
		let json = serde_json::to_string_pretty(&self)?;
		let mut fs = File::create(&self.file)?;
		fs.write_all(json.as_bytes())?;
		Ok(self)
	}

	/// Get a list of endpoints matching an optional filter. If not
	/// `chain` filter is passed, all endpoints are returned.
	pub fn get_endpoints(&self, chain: Option<&str>) -> HashSet<Endpoint> {
		let mut endpoint_vec: HashSet<Endpoint> = HashSet::new();
		self.registries.iter().for_each(|(_, reg)| {
			if !reg.enabled {
				// skipping
			} else {
				reg.rpc_endpoints
					.iter()
					.filter(|(c, _)| {
						if let Some(filter) = chain {
							c.as_str().to_ascii_lowercase() == filter.to_ascii_lowercase()
						} else {
							true
						}
					})
					.for_each(|(_, e)| {
						let ee = e.clone();
						endpoint_vec.extend(ee.into_iter());
					});
			}
		});
		endpoint_vec
	}

	/// Print the list of registries.
	///
	/// See also [Self::print_summary].
	pub fn print_registries(&self) {
		// println!("self.registries = {:?}", self.registries);
		self.registries.iter().for_each(|(_name, reg)| {
			println!("- [{}] {:?} {:?}", if reg.enabled { "X" } else { " " }, reg.name, reg.url);
		})
	}

	/// Print a summary of your local db. It shows more information than [Self::print_registries].
	pub fn print_summary(&self) {
		self.registries.iter().for_each(|(_name, reg)| {
			println!(
				"- [{}] {} - {}",
				if reg.enabled { "X" } else { " " },
				reg.name,
				if let Some(url) = &reg.url { url } else { "n/a" }
			);
			println!("      rpc endpoints: {:?}", reg.rpc_endpoints.len());
			println!("      last update: {:?}", reg.last_update);
		})
	}
}

impl Default for LocalData {
	fn default() -> Self {
		Self { file: Self::get_default_file(), registries: HashMap::new(), last_update: None }
	}
}

#[cfg(test)]
mod test_local_data {
	use super::*;

	#[test]
	fn test_builder() {
		let data = LocalData::init(&LocalData::get_default_file(), true)
            .expect("Forced init should work")
            .save()
            .expect("Saving data should work")
            .load().expect("Load works")
            .add_registry(Registry::new("SubRPC", "https://raw.githubusercontent.com/chevdor/subrpc/master/registry/subrpc.json"))
            .add_registry(Registry::new("SubRPC Gist", "https://gist.githubusercontent.com/chevdor/a8b381911c28f6de02dde62ed1a17dec/raw/6992b0a2924f80f691e4844c1731564f0e2a62ec/data.json"))
            .refresh()
            .save().expect("Saving works");
		println!("{data:#?}");
	}

	#[test]
	fn test_merge() {
		let data = LocalData::init(&LocalData::get_default_file(), true)
            .expect("Forced init should work")
            .add_registry(Registry::new("SubRPC Gist 1", "https://gist.githubusercontent.com/chevdor/a8b381911c28f6de02dde62ed1a17dec/raw/6992b0a2924f80f691e4844c1731564f0e2a62ec/data.json"))
            .add_registry(Registry::new("SubRPC Gist 2", "https://gist.githubusercontent.com/chevdor/a8b381911c28f6de02dde62ed1a17dec/raw/6992b0a2924f80f691e4844c1731564f0e2a62ec/data2.json"))
            .refresh()
            .save().expect("Saving works");
		assert_eq!(2, data.registries.len());
		println!("{data:#?}");
	}
}