use crate::fs as deno_fs;
use std::ffi::OsStr;
use std::fs;
use std::path::Component;
use std::path::Path;
use std::path::PathBuf;
use std::path::Prefix;
use std::str;
use url::Url;

#[derive(Clone)]
pub struct DiskCache {
  pub location: PathBuf,
}

impl DiskCache {
  pub fn new(location: &Path) -> Self {
    // TODO: ensure that 'location' is a directory
    Self {
      location: location.to_owned(),
    }
  }

  pub fn get_cache_filename(self: &Self, url: &Url) -> PathBuf {
    let mut out = PathBuf::new();

    let scheme = url.scheme();
    out.push(scheme);

    match scheme {
      "http" | "https" => {
        let host = url.host_str().unwrap();
        let host_port = match url.port() {
          // Windows doesn't support ":" in filenames, so we represent port using a
          // special string.
          Some(port) => format!("{}_PORT{}", host, port),
          None => host.to_string(),
        };
        out.push(host_port);

        for path_seg in url.path_segments().unwrap() {
          out.push(path_seg);
        }
      }
      "file" => {
        let path = url.to_file_path().unwrap();
        let mut path_components = path.components();

        if cfg!(target_os = "windows") {
          if let Some(Component::Prefix(prefix_component)) =
            path_components.next()
          {
            // Windows doesn't support ":" in filenames, so we need to extract disk prefix
            // Example: file:///C:/deno/js/unit_test_runner.ts
            // it should produce: file\c\deno\js\unit_test_runner.ts
            match prefix_component.kind() {
              Prefix::Disk(disk_byte) | Prefix::VerbatimDisk(disk_byte) => {
                let disk = (disk_byte as char).to_string();
                out.push(disk);
              }
              _ => unreachable!(),
            }
          }
        }

        // Must be relative, so strip forward slash
        let mut remaining_components = path_components.as_path();
        if let Ok(stripped) = remaining_components.strip_prefix("/") {
          remaining_components = stripped;
        };

        out = out.join(remaining_components);
      }
      scheme => {
        unimplemented!(
          "Don't know how to create cache name for scheme: {}",
          scheme
        );
      }
    };

    out
  }

  pub fn get_cache_filename_with_extension(
    self: &Self,
    url: &Url,
    extension: &str,
  ) -> PathBuf {
    let base = self.get_cache_filename(url);

    match base.extension() {
      None => base.with_extension(extension),
      Some(ext) => {
        let original_extension = OsStr::to_str(ext).unwrap();
        let final_extension = format!("{}.{}", original_extension, extension);
        base.with_extension(final_extension)
      }
    }
  }

  pub fn get(self: &Self, filename: &Path) -> std::io::Result<Vec<u8>> {
    let path = self.location.join(filename);
    fs::read(&path)
  }

  pub fn set(self: &Self, filename: &Path, data: &[u8]) -> std::io::Result<()> {
    let path = self.location.join(filename);
    match path.parent() {
      Some(ref parent) => fs::create_dir_all(parent),
      None => Ok(()),
    }?;
    deno_fs::write_file(&path, data, 0o666)
  }

  pub fn remove(self: &Self, filename: &Path) -> std::io::Result<()> {
    let path = self.location.join(filename);
    fs::remove_file(path)
  }
}

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

  #[test]
  fn test_get_cache_filename() {
    let cache_location = if cfg!(target_os = "windows") {
      PathBuf::from(r"C:\deno_dir\")
    } else {
      PathBuf::from("/deno_dir/")
    };

    let cache = DiskCache::new(&cache_location);

    let mut test_cases = vec![
      (
        "http://deno.land/std/http/file_server.ts",
        "http/deno.land/std/http/file_server.ts",
      ),
      (
        "http://localhost:8000/std/http/file_server.ts",
        "http/localhost_PORT8000/std/http/file_server.ts",
      ),
      (
        "https://deno.land/std/http/file_server.ts",
        "https/deno.land/std/http/file_server.ts",
      ),
    ];

    if cfg!(target_os = "windows") {
      test_cases.push(("file:///D:/a/1/s/format.ts", "file/D/a/1/s/format.ts"));
    } else {
      test_cases.push((
        "file:///std/http/file_server.ts",
        "file/std/http/file_server.ts",
      ));
    }

    for test_case in &test_cases {
      let cache_filename =
        cache.get_cache_filename(&Url::parse(test_case.0).unwrap());
      assert_eq!(cache_filename, PathBuf::from(test_case.1));
    }
  }

  #[test]
  fn test_get_cache_filename_with_extension() {
    let cache = DiskCache::new(&PathBuf::from("foo"));

    let mut test_cases = vec![
      (
        "http://deno.land/std/http/file_server.ts",
        "js",
        "http/deno.land/std/http/file_server.ts.js",
      ),
      (
        "http://deno.land/std/http/file_server.ts",
        "js.map",
        "http/deno.land/std/http/file_server.ts.js.map",
      ),
    ];

    if cfg!(target_os = "windows") {
      test_cases.push((
        "file:///D:/std/http/file_server",
        "js",
        "file/D/std/http/file_server.js",
      ));
    } else {
      test_cases.push((
        "file:///std/http/file_server",
        "js",
        "file/std/http/file_server.js",
      ));
    }

    for test_case in &test_cases {
      assert_eq!(
        cache.get_cache_filename_with_extension(
          &Url::parse(test_case.0).unwrap(),
          test_case.1
        ),
        PathBuf::from(test_case.2)
      )
    }
  }
}