// Copyright (c) Zefchain Labs, Inc.
// SPDX-License-Identifier: Apache-2.0

use std::{
    io::Write,
    path::{Path, PathBuf},
    process::Command,
};

use anyhow::{ensure, Context, Result};
use cargo_toml::Manifest;
use convert_case::{Case, Casing};
use current_platform::CURRENT_PLATFORM;
use fs_err::File;
use tracing::debug;

pub struct Project {
    root: PathBuf,
}

impl Project {
    pub fn create_new(name: &str, linera_root: Option<&Path>) -> Result<Self> {
        ensure!(
            !name.contains(std::path::is_separator),
            "Project name {name} should not contain path-separators",
        );
        let root = PathBuf::from(name);
        ensure!(
            !root.exists(),
            "Directory {} already exists",
            root.display(),
        );
        ensure!(
            root.extension().is_none(),
            "Project name {name} should not have a file extension",
        );
        debug!("Creating directory at {}", root.display());
        fs_err::create_dir_all(&root)?;

        debug!("Creating the source directory");
        let source_directory = Self::create_source_directory(&root)?;

        debug!("Creating the tests directory");
        let test_directory = Self::create_test_directory(&root)?;

        debug!("Initializing git repository");
        Self::initialize_git_repository(&root)?;

        debug!("Writing Cargo.toml");
        Self::create_cargo_toml(&root, name, linera_root)?;

        debug!("Writing rust-toolchain.toml");
        Self::create_rust_toolchain(&root)?;

        debug!("Writing state.rs");
        Self::create_state_file(&source_directory, name)?;

        debug!("Writing lib.rs");
        Self::create_lib_file(&source_directory, name)?;

        debug!("Writing contract.rs");
        Self::create_contract_file(&source_directory, name)?;

        debug!("Writing service.rs");
        Self::create_service_file(&source_directory, name)?;

        debug!("Writing single_chain.rs");
        Self::create_test_file(&test_directory, name)?;

        Ok(Self { root })
    }

    pub fn from_existing_project(root: PathBuf) -> Result<Self> {
        ensure!(
            root.exists(),
            "could not find project at {}",
            root.display()
        );
        Ok(Self { root })
    }

    /// Runs the unit and integration tests of an application.
    pub async fn test(&self) -> Result<()> {
        let tests = Command::new("cargo")
            .arg("test")
            .args(["--target", CURRENT_PLATFORM])
            .current_dir(&self.root)
            .spawn()?
            .wait()?;
        ensure!(tests.success(), "tests failed");
        Ok(())
    }

    /// Finds the workspace for a given crate. If the workspace
    /// does not exist, returns the path of the crate.
    fn workspace_root(&self) -> Result<&Path> {
        let mut current_path = self.root.as_path();
        loop {
            let toml_path = current_path.join("Cargo.toml");
            if toml_path.exists() {
                let toml = Manifest::from_path(toml_path)?;
                if toml.workspace.is_some() {
                    return Ok(current_path);
                }
            }
            match current_path.parent() {
                None => {
                    break;
                }
                Some(parent) => current_path = parent,
            }
        }
        Ok(self.root.as_path())
    }

    fn create_source_directory(project_root: &Path) -> Result<PathBuf> {
        let source_directory = project_root.join("src");
        fs_err::create_dir(&source_directory)?;
        Ok(source_directory)
    }

    fn create_test_directory(project_root: &Path) -> Result<PathBuf> {
        let test_directory = project_root.join("tests");
        fs_err::create_dir(&test_directory)?;
        Ok(test_directory)
    }

    fn initialize_git_repository(project_root: &Path) -> Result<()> {
        let output = Command::new("git")
            .args([
                "init",
                project_root
                    .to_str()
                    .context("project name contains non UTF-8 characters")?,
            ])
            .output()?;

        ensure!(
            output.status.success(),
            "failed to initialize git repository at {}",
            &project_root.display()
        );

        Self::write_string_to_file(&project_root.join(".gitignore"), "/target")
    }

    fn create_cargo_toml(
        project_root: &Path,
        project_name: &str,
        linera_root: Option<&Path>,
    ) -> Result<()> {
        let toml_path = project_root.join("Cargo.toml");
        let (linera_sdk_dep, linera_sdk_dev_dep) = Self::linera_sdk_dependencies(linera_root);
        let binary_root_name = project_name.replace('-', "_");
        let contract_binary_name = format!("{binary_root_name}_contract");
        let service_binary_name = format!("{binary_root_name}_service");
        let toml_contents = format!(
            include_str!("../template/Cargo.toml.template"),
            project_name = project_name,
            contract_binary_name = contract_binary_name,
            service_binary_name = service_binary_name,
            linera_sdk_dep = linera_sdk_dep,
            linera_sdk_dev_dep = linera_sdk_dev_dep,
        );
        Self::write_string_to_file(&toml_path, &toml_contents)
    }

    fn create_rust_toolchain(project_root: &Path) -> Result<()> {
        Self::write_string_to_file(
            &project_root.join("rust-toolchain.toml"),
            include_str!("../template/rust-toolchain.toml.template"),
        )
    }

    fn create_state_file(source_directory: &Path, project_name: &str) -> Result<()> {
        let project_name = project_name.to_case(Case::Pascal);
        let state_path = source_directory.join("state.rs");
        let file_content = format!(
            include_str!("../template/state.rs.template"),
            project_name = project_name
        );
        Self::write_string_to_file(&state_path, &file_content)
    }

    fn create_lib_file(source_directory: &Path, project_name: &str) -> Result<()> {
        let project_name = project_name.to_case(Case::Pascal);
        let state_path = source_directory.join("lib.rs");
        let file_content = format!(
            include_str!("../template/lib.rs.template"),
            project_name = project_name
        );
        Self::write_string_to_file(&state_path, &file_content)
    }

    fn create_contract_file(source_directory: &Path, name: &str) -> Result<()> {
        let project_name = name.to_case(Case::Pascal);
        let contract_path = source_directory.join("contract.rs");
        let contract_contents = format!(
            include_str!("../template/contract.rs.template"),
            module_name = name.replace('-', "_"),
            project_name = project_name
        );
        Self::write_string_to_file(&contract_path, &contract_contents)
    }

    fn create_service_file(source_directory: &Path, name: &str) -> Result<()> {
        let project_name = name.to_case(Case::Pascal);
        let service_path = source_directory.join("service.rs");
        let service_contents = format!(
            include_str!("../template/service.rs.template"),
            module_name = name.replace('-', "_"),
            project_name = project_name
        );
        Self::write_string_to_file(&service_path, &service_contents)
    }

    fn create_test_file(test_directory: &Path, name: &str) -> Result<()> {
        let project_name = name.to_case(Case::Pascal);
        let test_path = test_directory.join("single_chain.rs");
        let test_contents = format!(
            include_str!("../template/tests/single_chain.rs.template"),
            project_name = name.replace('-', "_"),
            project_abi = project_name,
        );
        Self::write_string_to_file(&test_path, &test_contents)
    }

    fn write_string_to_file(path: &Path, content: &str) -> Result<()> {
        let mut file = File::create(path)?;
        file.write_all(content.as_bytes())?;
        Ok(())
    }

    /// Resolves [`linera_sdk`] and [`linera_views`] dependencies.
    fn linera_sdk_dependencies(linera_root: Option<&Path>) -> (String, String) {
        match linera_root {
            Some(path) => Self::linera_sdk_testing_dependencies(path),
            None => Self::linera_sdk_production_dependencies(),
        }
    }

    /// Resolves [`linera_sdk`] and [`linera_views`] dependencies in testing mode.
    fn linera_sdk_testing_dependencies(linera_root: &Path) -> (String, String) {
        // We're putting the Cargo.toml file one level above the current directory.
        let linera_root = PathBuf::from("..").join(linera_root);
        let linera_sdk_path = linera_root.join("linera-sdk");
        let linera_sdk_dep = format!(
            "linera-sdk = {{ path = \"{}\" }}",
            linera_sdk_path.display()
        );
        let linera_sdk_dev_dep = format!(
            "linera-sdk = {{ path = \"{}\", features = [\"test\", \"wasmer\"] }}",
            linera_sdk_path.display()
        );
        (linera_sdk_dep, linera_sdk_dev_dep)
    }

    /// Adds [`linera_sdk`] dependencies in production mode.
    fn linera_sdk_production_dependencies() -> (String, String) {
        let version = env!("CARGO_PKG_VERSION");
        let linera_sdk_dep = format!("linera-sdk = \"{}\"", version);
        let linera_sdk_dev_dep = format!(
            "linera-sdk = {{ version = \"{}\", features = [\"test\", \"wasmer\"] }}",
            version
        );
        (linera_sdk_dep, linera_sdk_dev_dep)
    }

    pub fn build(&self, name: Option<String>) -> Result<(PathBuf, PathBuf), anyhow::Error> {
        let name = match name {
            Some(name) => name,
            None => self.project_package_name()?.replace('-', "_"),
        };
        let contract_name = format!("{}_contract", name);
        let service_name = format!("{}_service", name);
        let cargo_build = Command::new("cargo")
            .arg("build")
            .arg("--release")
            .args(["--target", "wasm32-unknown-unknown"])
            .current_dir(&self.root)
            .spawn()?
            .wait()?;
        ensure!(cargo_build.success(), "build failed");
        let build_path = self
            .workspace_root()?
            .join("target/wasm32-unknown-unknown/release");
        Ok((
            build_path.join(contract_name).with_extension("wasm"),
            build_path.join(service_name).with_extension("wasm"),
        ))
    }

    fn project_package_name(&self) -> Result<String> {
        let manifest = Manifest::from_path(self.cargo_toml_path())?;
        let name = manifest
            .package
            .context("Cargo.toml is missing `[package]`")?
            .name;
        Ok(name)
    }

    fn cargo_toml_path(&self) -> PathBuf {
        self.root.join("Cargo.toml")
    }
}