// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.

use crate::NodeModuleKind;

use super::RequireNpmResolver;
use deno_core::anyhow;
use deno_core::anyhow::bail;
use deno_core::error::AnyError;
use deno_core::serde_json;
use deno_core::serde_json::Map;
use deno_core::serde_json::Value;
use serde::Serialize;
use std::io::ErrorKind;
use std::path::PathBuf;

#[derive(Clone, Debug, Serialize)]
pub struct PackageJson {
  pub exists: bool,
  pub exports: Option<Map<String, Value>>,
  pub imports: Option<Map<String, Value>>,
  pub bin: Option<Value>,
  main: Option<String>,   // use .main(...)
  module: Option<String>, // use .main(...)
  pub name: Option<String>,
  pub version: Option<String>,
  pub path: PathBuf,
  pub typ: String,
  pub types: Option<String>,
}

impl PackageJson {
  pub fn empty(path: PathBuf) -> PackageJson {
    PackageJson {
      exists: false,
      exports: None,
      imports: None,
      bin: None,
      main: None,
      module: None,
      name: None,
      version: None,
      path,
      typ: "none".to_string(),
      types: None,
    }
  }

  pub fn load(
    resolver: &dyn RequireNpmResolver,
    path: PathBuf,
  ) -> Result<PackageJson, AnyError> {
    resolver.ensure_read_permission(&path)?;
    Self::load_skip_read_permission(path)
  }

  pub fn load_skip_read_permission(
    path: PathBuf,
  ) -> Result<PackageJson, AnyError> {
    let source = match std::fs::read_to_string(&path) {
      Ok(source) => source,
      Err(err) if err.kind() == ErrorKind::NotFound => {
        return Ok(PackageJson::empty(path));
      }
      Err(err) => bail!(
        "Error loading package.json at {}. {:#}",
        path.display(),
        err
      ),
    };

    if source.trim().is_empty() {
      return Ok(PackageJson::empty(path));
    }

    let package_json: Value = serde_json::from_str(&source)
      .map_err(|err| anyhow::anyhow!("malformed package.json {}", err))?;

    let imports_val = package_json.get("imports");
    let main_val = package_json.get("main");
    let module_val = package_json.get("module");
    let name_val = package_json.get("name");
    let version_val = package_json.get("version");
    let type_val = package_json.get("type");
    let bin = package_json.get("bin").map(ToOwned::to_owned);
    let exports = package_json.get("exports").map(|exports| {
      if is_conditional_exports_main_sugar(exports) {
        let mut map = Map::new();
        map.insert(".".to_string(), exports.to_owned());
        map
      } else {
        exports.as_object().unwrap().to_owned()
      }
    });

    let imports = imports_val
      .and_then(|imp| imp.as_object())
      .map(|imp| imp.to_owned());
    let main = main_val.and_then(|s| s.as_str()).map(|s| s.to_string());
    let name = name_val.and_then(|s| s.as_str()).map(|s| s.to_string());
    let version = version_val.and_then(|s| s.as_str()).map(|s| s.to_string());
    let module = module_val.and_then(|s| s.as_str()).map(|s| s.to_string());

    // Ignore unknown types for forwards compatibility
    let typ = if let Some(t) = type_val {
      if let Some(t) = t.as_str() {
        if t != "module" && t != "commonjs" {
          "none".to_string()
        } else {
          t.to_string()
        }
      } else {
        "none".to_string()
      }
    } else {
      "none".to_string()
    };

    // for typescript, it looks for "typings" first, then "types"
    let types = package_json
      .get("typings")
      .or_else(|| package_json.get("types"))
      .and_then(|t| t.as_str().map(|s| s.to_string()));

    let package_json = PackageJson {
      exists: true,
      path,
      main,
      name,
      version,
      module,
      typ,
      types,
      exports,
      imports,
      bin,
    };
    Ok(package_json)
  }

  pub fn main(&self, referrer_kind: NodeModuleKind) -> Option<&String> {
    if referrer_kind == NodeModuleKind::Esm && self.typ == "module" {
      self.module.as_ref().or(self.main.as_ref())
    } else {
      self.main.as_ref()
    }
  }
}

fn is_conditional_exports_main_sugar(exports: &Value) -> bool {
  if exports.is_string() || exports.is_array() {
    return true;
  }

  if exports.is_null() || !exports.is_object() {
    return false;
  }

  let exports_obj = exports.as_object().unwrap();
  let mut is_conditional_sugar = false;
  let mut i = 0;
  for key in exports_obj.keys() {
    let cur_is_conditional_sugar = key.is_empty() || !key.starts_with('.');
    if i == 0 {
      is_conditional_sugar = cur_is_conditional_sugar;
      i += 1;
    } else if is_conditional_sugar != cur_is_conditional_sugar {
      panic!("\"exports\" cannot contains some keys starting with \'.\' and some not.
        The exports object must either be an object of package subpath keys
        or an object of main entry condition name keys only.")
    }
  }

  is_conditional_sugar
}