// Copyright 2022 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

use std::{collections::HashMap, path::PathBuf};

use serde::{Deserialize, Serialize};

/// Top-level manifest file for a project.
#[derive(Debug, Deserialize, Serialize)]
pub struct Manifest {
    /// Information about the project to which the manifest belongs.
    pub project: Project,

    /// Additional target providers defined by the project.
    #[serde(default)]
    pub providers: HashMap<String, ProviderDescriptor>,

    /// Targets provided directly by the project.
    #[serde(default)]
    pub targets: HashMap<String, Target>,
}

/// A qg-based project.
#[derive(Debug, Deserialize, Serialize)]
pub struct Project {
    /// The name of the project.
    pub name: String,
}

/// Scoping of targets in a provider.
#[derive(Debug, Deserialize, Eq, PartialEq, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum ProviderNamespace {
    /// Targets are namespaced under the provider.
    Local,

    /// Targets appear in the global namespace.
    Global,
}

impl Default for ProviderNamespace {
    fn default() -> Self {
        Self::Local
    }
}

impl ProviderNamespace {
    pub fn is_global(&self) -> bool {
        self == &Self::Global
    }
}

/// Information about a target provider.
#[derive(Debug, Deserialize, Serialize)]
pub struct ProviderDescriptor {
    /// Path to a file in which the provider is defined.
    pub manifest: Option<PathBuf>,

    /// Default scoping of the provider's targets.
    #[serde(default)]
    pub namespace: ProviderNamespace,
}

/// Manifest file defining a target provider.
#[derive(Debug, Deserialize, Serialize)]
pub struct ProviderFile {
    /// Metadata about the provider.
    pub provider: Option<ProviderDescriptor>,

    /// Targets defined by the provider.
    #[serde(default)]
    pub targets: HashMap<String, Target>,
}

/// A buildable target.
#[derive(Debug, Deserialize, Serialize)]
pub struct Target {
    /// Provider-specific metadata about how to build the target. If this is
    /// `None`, the target is virtual, grouping only other target dependencies.
    #[serde(flatten)]
    pub desc: Option<TargetType>,

    /// Scope of the target. Overrides the default provider scope.
    #[serde(default)]
    pub namespace: ProviderNamespace,

    /// List of other targets on which this one depends.
    #[serde(default)]
    pub deps: Vec<String>,
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum TargetType {
    Cipd(CipdPackage),
    Download(DownloadablePackage),
    #[cfg(test)]
    Fake(FakeTarget),
}

/// A downloadable CIPD package.
#[derive(Debug, Deserialize, Serialize)]
pub struct CipdPackage {
    /// The location on of the package in CIPD's repositories.
    pub path: String,

    /// Platforms the package supports.
    #[serde(default)]
    pub platforms: Vec<String>,

    /// CIPD tags to match against when finding a package revision.
    #[serde(default)]
    pub tags: Vec<String>,

    /// Local subdirectory under the CIPD installation root into which the
    /// package is installed.
    pub subdir: Option<PathBuf>,
}

/// A package downloadable from a known URL.
#[derive(Debug, Deserialize, Serialize)]
pub struct DownloadablePackage {
    /// The URL at which the package is located.
    ///
    /// The URL may define arbitrary parameters enclosed in braces, which will
    /// be interpolated with values from the `url_parameters` field.
    ///
    /// For example, the URL `https://api.left-pad.io?str={string}&len={length}`
    /// will substitute the values of `string` and `length` defined within
    /// `url_parameters` into the appropriate query params.
    pub url: String,

    /// Variable substitutions for `url`. See its documentation for details.
    #[serde(default)]
    pub url_parameters: HashMap<String, String>,

    /// Overrides for the `url_parameters` field. Overrides are processed in
    /// order of definition, with the first match being applied.
    #[serde(default)]
    pub variants: Vec<DownloadVariants>,

    /// File format of the downloaded file. One of:
    ///
    ///   - `bin`: An uncompressed executable file.
    ///
    pub format: Option<String>,

    // For a `bin` format, what to rename the downloaded binary.
    pub bin_name: Option<PathBuf>,
}

/// An override of the default `url_parameters` for a downloadable package.
#[derive(Debug, Deserialize, Serialize)]
pub struct DownloadVariants {
    /// Mapping of variable -> value against which this override is matched.
    /// The matchable variables are:
    ///
    ///   * `os`: The system on which the build is running. One of `linux`,
    ///     `macos`, or `windows`.
    ///   * `arch`: System architecture. Either `x64` or `arm64`.
    ///
    #[serde(default, rename = "match")]
    pub match_vars: HashMap<String, String>,

    /// Parameter overrides to apply if this variant is matched.
    #[serde(default)]
    pub url_parameters: HashMap<String, String>,
}

/// A fake target for testing.
#[derive(Debug, Deserialize, Serialize)]
#[cfg(test)]
pub struct FakeTarget {
    /// The number of unitless ticks this target takes to execute.
    pub duration_ticks: u32,
}

impl Manifest {
    pub fn new(name: &str) -> Self {
        Self {
            project: Project {
                name: name.to_owned(),
            },
            providers: HashMap::new(),
            targets: HashMap::new(),
        }
    }
}