use std::collections::{HashMap, HashSet, VecDeque};
use std::fs::File;
use std::io::{BufWriter, Write};
use std::path::{Path, PathBuf};

use anyhow::{Context, Result};

use indoc::formatdoc;
use serde::{Deserialize, Serialize};

use crate::configuration_file::ConfigurationFile;
use crate::io::read_json_from_file;

#[derive(Serialize, Deserialize, Clone, Debug)]
#[serde(rename_all = "camelCase")]
pub struct PackageManifestFile {
    pub name: String,
    pub version: String,
    #[serde(flatten)]
    pub extra_fields: serde_json::Value,
}

#[derive(Clone, Debug)]
pub struct PackageManifest {
    monorepo_root: PathBuf,
    directory: PathBuf,
    pub contents: PackageManifestFile,
}

pub enum DependencyGroup {
    Dependencies,
    DevDependencies,
    OptionalDependencies,
    PeerDependencies,
}

impl DependencyGroup {
    pub const VALUES: [Self; 4] = [
        Self::Dependencies,
        Self::DevDependencies,
        Self::OptionalDependencies,
        Self::PeerDependencies,
    ];
}

impl ConfigurationFile<PackageManifest> for PackageManifest {
    const FILENAME: &'static str = "package.json";

    fn from_directory(monorepo_root: &Path, directory: &Path) -> Result<PackageManifest> {
        let filename = monorepo_root.join(directory).join(Self::FILENAME);
        let manifest_contents: PackageManifestFile =
            read_json_from_file(&filename).with_context(|| {
                formatdoc!(
                    "
                    Unexpected contents in {:?}

                    I'm trying to parse the following properties and values out
                    of this package.json file:

                    - name: string
                    - version: string

                    and if any of the following values are present, I expect
                    them to be a JSON object with string keys and string values:

                    - dependencies
                    - devDependencies
                    - optionalDependencies
                    - peerDependencies
                    ",
                    filename
                )
            })?;
        Ok(PackageManifest {
            monorepo_root: monorepo_root.to_owned(),
            directory: directory.to_owned(),
            contents: manifest_contents,
        })
    }

    fn directory(&self) -> PathBuf {
        self.directory.to_owned()
    }

    fn path(&self) -> PathBuf {
        self.directory.join(Self::FILENAME)
    }

    fn write(&self) -> Result<()> {
        let file = File::create(
            self.monorepo_root
                .join(&self.directory)
                .join(Self::FILENAME),
        )?;
        let mut writer = BufWriter::new(file);
        serde_json::to_writer_pretty(&mut writer, &self.contents)?;
        writer.write_all(b"\n")?;
        writer.flush()?;
        Ok(())
    }
}

impl AsRef<PackageManifest> for PackageManifest {
    fn as_ref(&self) -> &Self {
        self
    }
}

impl PackageManifest {
    // Get the dependency
    pub fn get_dependency_version<S>(&self, dependency: S) -> Option<String>
    where
        S: AsRef<str>,
    {
        static DEPENDENCY_GROUPS: &[&str] = &[
            "dependencies",
            "devDependencies",
            "optionalDependencies",
            "peerDependencies",
        ];

        DEPENDENCY_GROUPS
            .iter()
            // only iterate over the objects corresponding to each dependency group
            .filter_map(|dependency_group| {
                self.contents
                    .extra_fields
                    .get(dependency_group)?
                    .as_object()
            })
            // get the target dependency version, if exists
            .filter_map(|dependency_group_value| {
                dependency_group_value
                    .get(dependency.as_ref())
                    .and_then(|version_value| version_value.as_str().map(|a| a.to_owned()))
            })
            .take(1)
            .next()
    }

    pub fn internal_dependencies_iter<'a>(
        &'a self,
        package_manifests_by_package_name: &'a HashMap<String, PackageManifest>,
    ) -> impl Iterator<Item = &'a PackageManifest> {
        static DEPENDENCY_GROUPS: &[&str] = &[
            "dependencies",
            "devDependencies",
            "optionalDependencies",
            "peerDependencies",
        ];

        DEPENDENCY_GROUPS
            .iter()
            // only iterate over the objects corresponding to each dependency group
            .filter_map(|dependency_group| {
                self.contents
                    .extra_fields
                    .get(dependency_group)?
                    .as_object()
            })
            // get all dependency names from all groups
            .flat_map(|dependency_group_value| dependency_group_value.keys())
            // filter out external packages
            .filter_map(|package_name| package_manifests_by_package_name.get(package_name))
    }

    pub fn transitive_internal_dependency_package_names_exclusive<'a>(
        &self,
        package_manifest_by_package_name: &'a HashMap<String, PackageManifest>,
    ) -> Vec<&'a PackageManifest> {
        // Depth-first search all transitive internal dependencies of package
        let mut seen_package_names = HashSet::new();
        let mut internal_dependencies = HashSet::new();
        let mut to_visit_package_manifests = VecDeque::new();

        to_visit_package_manifests.push_back(self);

        while let Some(current_manifest) = to_visit_package_manifests.pop_front() {
            seen_package_names.insert(&current_manifest.contents.name);

            for dependency in
                current_manifest.internal_dependencies_iter(package_manifest_by_package_name)
            {
                internal_dependencies.insert(dependency.contents.name.to_owned());
                if !seen_package_names.contains(&dependency.contents.name) {
                    to_visit_package_manifests.push_back(dependency);
                }
            }
        }

        internal_dependencies
            .iter()
            .map(|dependency_package_name| {
                package_manifest_by_package_name
                    .get(dependency_package_name)
                    .unwrap()
            })
            .collect()
    }

    pub fn get_dependency_group_mut(
        &mut self,
        group: &DependencyGroup,
    ) -> Option<&mut serde_json::Map<String, serde_json::Value>> {
        let group_index = match group {
            DependencyGroup::Dependencies => "dependencies",
            DependencyGroup::DevDependencies => "devDependencies",
            DependencyGroup::OptionalDependencies => "optionalDependencies",
            DependencyGroup::PeerDependencies => "peerDependencies",
        };
        self.contents
            .extra_fields
            .get_mut(group_index)
            .and_then(serde_json::Value::as_object_mut)
    }

    // Name of the archive generated by `npm pack`, for example "myscope-a-cool-package-1.0.0.tgz"
    pub fn npm_pack_file_basename(&self) -> String {
        format!(
            "{}-{}.tgz",
            self.contents.name.trim_start_matches('@').replace('/', "-"),
            &self.contents.version,
        )
    }

    pub fn unscoped_package_name(&self) -> &str {
        match &self.contents.name.rsplit_once('/') {
            Some((_scope, name)) => name,
            None => &self.contents.name,
        }
    }
}