// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.

use std::collections::HashMap;
use std::path::PathBuf;
use std::sync::Arc;

use deno_core::anyhow::bail;
use deno_core::anyhow::Context;
use deno_core::error::AnyError;
use deno_core::futures::stream::FuturesOrdered;
use deno_core::futures::StreamExt;
use deno_core::parking_lot::Mutex;
use deno_npm::registry::NpmRegistryApi;
use deno_npm::resolution::SerializedNpmResolutionSnapshot;
use deno_npm::resolution::SerializedNpmResolutionSnapshotPackage;
use deno_npm::resolution::ValidSerializedNpmResolutionSnapshot;
use deno_npm::NpmPackageId;
use deno_npm::NpmResolutionPackageSystemInfo;
use deno_semver::npm::NpmPackageReq;

use crate::args::ConfigFile;
use crate::npm::CliNpmRegistryApi;
use crate::Flags;

use super::DenoSubcommand;

pub use deno_lockfile::Lockfile;
pub use deno_lockfile::LockfileError;

pub fn discover(
  flags: &Flags,
  maybe_config_file: Option<&ConfigFile>,
) -> Result<Option<Lockfile>, AnyError> {
  if flags.no_lock
    || matches!(
      flags.subcommand,
      DenoSubcommand::Install(_) | DenoSubcommand::Uninstall(_)
    )
  {
    return Ok(None);
  }

  let filename = match flags.lock {
    Some(ref lock) => PathBuf::from(lock),
    None => match maybe_config_file {
      Some(config_file) => {
        if config_file.specifier.scheme() == "file" {
          match config_file.resolve_lockfile_path()? {
            Some(path) => path,
            None => return Ok(None),
          }
        } else {
          return Ok(None);
        }
      }
      None => return Ok(None),
    },
  };

  let lockfile = Lockfile::new(filename, flags.lock_write)?;
  Ok(Some(lockfile))
}

pub async fn snapshot_from_lockfile(
  lockfile: Arc<Mutex<Lockfile>>,
  api: &CliNpmRegistryApi,
) -> Result<ValidSerializedNpmResolutionSnapshot, AnyError> {
  let (root_packages, mut packages) = {
    let lockfile = lockfile.lock();

    let mut root_packages =
      HashMap::<NpmPackageReq, NpmPackageId>::with_capacity(
        lockfile.content.npm.specifiers.len(),
      );
    // collect the specifiers to version mappings
    for (key, value) in &lockfile.content.npm.specifiers {
      let package_req = NpmPackageReq::from_str(key)
        .with_context(|| format!("Unable to parse npm specifier: {key}"))?;
      let package_id = NpmPackageId::from_serialized(value)?;
      root_packages.insert(package_req, package_id.clone());
    }

    // now fill the packages except for the dist information
    let mut packages = Vec::with_capacity(lockfile.content.npm.packages.len());
    for (key, package) in &lockfile.content.npm.packages {
      let id = NpmPackageId::from_serialized(key)?;

      // collect the dependencies
      let mut dependencies = HashMap::with_capacity(package.dependencies.len());
      for (name, specifier) in &package.dependencies {
        let dep_id = NpmPackageId::from_serialized(specifier)?;
        dependencies.insert(name.clone(), dep_id);
      }

      packages.push(SerializedNpmResolutionSnapshotPackage {
        id,
        dependencies,
        // temporarily empty
        system: Default::default(),
        dist: Default::default(),
        optional_dependencies: Default::default(),
      });
    }
    (root_packages, packages)
  };

  // now that the lockfile is dropped, fetch the package version information
  let pkg_nvs = packages.iter().map(|p| p.id.nv.clone()).collect::<Vec<_>>();
  let get_version_infos = || {
    FuturesOrdered::from_iter(pkg_nvs.iter().map(|nv| async move {
      let package_info = api.package_info(&nv.name).await?;
      match package_info.version_info(nv) {
        Ok(version_info) => Ok(version_info),
        Err(err) => {
          bail!("Could not find '{}' specified in the lockfile.", err.0);
        }
      }
    }))
  };
  let mut version_infos = get_version_infos();
  let mut i = 0;
  while let Some(result) = version_infos.next().await {
    match result {
      Ok(version_info) => {
        let package = &mut packages[i];
        package.dist = version_info.dist;
        package.system = NpmResolutionPackageSystemInfo {
          cpu: version_info.cpu,
          os: version_info.os,
        };
        package.optional_dependencies =
          version_info.optional_dependencies.into_keys().collect();
      }
      Err(err) => {
        if api.mark_force_reload() {
          // reset and try again
          version_infos = get_version_infos();
          i = 0;
          continue;
        } else {
          return Err(err);
        }
      }
    }

    i += 1;
  }

  // clear the memory cache to reduce memory usage
  api.clear_memory_cache();

  SerializedNpmResolutionSnapshot {
    packages,
    root_packages,
  }
  .into_valid()
  .context("The lockfile is corrupt. You can recreate it with --lock-write")
}