// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: 2023 The Gleam contributors

use debug_ignore::DebugIgnore;
use ecow::EcoString;
use itertools::Itertools;

use gleam_core::{
    Error, Result, Warning,
    analyse::TargetSupport,
    build::{self, Mode, Module, NullTelemetry, Outcome, ProjectCompiler},
    config::PackageConfig,
    io::{BeamCompilerIO, CommandExecutor, FileSystemReader, FileSystemWriter, Stdio},
    line_numbers::LineNumbers,
    manifest::Manifest,
    paths::ProjectPaths,
    type_::ModuleInterface,
    warning::VectorWarningEmitterIO,
};
use std::{collections::HashMap, rc::Rc};

use camino::Utf8PathBuf;

use super::{LockGuard, Locker};

/// A wrapper around the project compiler which makes it possible to repeatedly
/// recompile the top level package, reusing the information about the already
/// compiled dependency packages.
///
#[derive(Debug)]
pub struct LspProjectCompiler<IO> {
    pub project_compiler: ProjectCompiler<IO>,

    /// Information on compiled modules.
    pub modules: HashMap<EcoString, Module>,
    pub sources: HashMap<EcoString, ModuleSourceInformation>,

    /// The storage for the warning emitter.
    pub warnings: Rc<VectorWarningEmitterIO>,

    /// A lock to ensure that multiple instances of the LSP don't try and use
    /// build directory at the same time.
    pub locker: DebugIgnore<Box<dyn Locker>>,
}

impl<IO> LspProjectCompiler<IO>
where
    IO: CommandExecutor + FileSystemWriter + FileSystemReader + BeamCompilerIO + Clone,
{
    pub fn new(
        manifest: Manifest,
        config: PackageConfig,
        paths: ProjectPaths,
        io: IO,
        locker: Box<dyn Locker>,
    ) -> Result<Self> {
        let target = config.target;
        let name = config.name.clone();
        let warnings = Rc::new(VectorWarningEmitterIO::default());

        // The build caches do not contain all the information we need in the
        // LSP (e.g. the typed AST) so delete the caches for the top level
        // package before we run for the first time.
        {
            let _guard: LockGuard = locker.lock_for_build()?;
            let path = paths.build_directory_for_package(Mode::Lsp, target, &name);
            io.delete_directory(&path)?;
        }

        let options = build::Options {
            warnings_as_errors: false,
            mode: Mode::Lsp,
            target: None,
            codegen: build::Codegen::None,
            compile: build::Compile::All,
            root_target_support: TargetSupport::Enforced,
            no_print_progress: false,
        };
        let mut project_compiler = ProjectCompiler::new(
            config,
            options,
            manifest.packages,
            &NullTelemetry,
            warnings.clone(),
            paths,
            io,
        );

        // To avoid the Erlang compiler printing to stdout (and thus
        // violating LSP which is currently using stdout) we silence it.
        project_compiler.subprocess_stdio = Stdio::Null;

        Ok(Self {
            locker: locker.into(),
            warnings,
            project_compiler,
            modules: HashMap::new(),
            sources: HashMap::new(),
        })
    }

    pub fn compile(&mut self) -> Outcome<Vec<Utf8PathBuf>, Error> {
        // Lock the build directory to ensure to ensure we are the only one compiling
        let _lock_guard: LockGuard = match self.locker.lock_for_build() {
            Ok(it) => it,
            Err(err) => return err.into(),
        };

        // Verify that the build directory was created using the same version of
        // Gleam as we are running. If it is not then we discard the build
        // directory as the cache files may be in a different format.
        if let Err(e) = self
            .project_compiler
            .check_gleam_version_and_build_configuration()
        {
            return e.into();
        }

        self.project_compiler.reset_state_for_new_compile_run();

        let compiled_dependencies = match self.project_compiler.compile_dependencies() {
            Ok(it) => it,
            Err(err) => return err.into(),
        };

        // Store the compiled dependency module information
        for module in &compiled_dependencies {
            let path = module.input_path.as_os_str().to_string_lossy().to_string();
            // strip canonicalised windows prefix
            #[cfg(target_family = "windows")]
            let path = path
                .strip_prefix(r"\\?\")
                .map(|s| s.to_string())
                .unwrap_or(path);
            let line_numbers = LineNumbers::new(&module.code);
            let source = ModuleSourceInformation { path, line_numbers };
            _ = self.sources.insert(module.name.clone(), source);
        }

        // Since cached modules are not recompiled we need to manually add them
        for (name, module) in self.project_compiler.get_importable_modules() {
            // It we already have the source for an importable module it means
            // that we already have all the information we are adding here, so
            // we can skip past to to avoid doing extra work for no gain.
            if self.sources.contains_key(name) || name == "gleam" {
                continue;
            }
            // Create the source information
            let path = module.src_path.to_string();
            // strip canonicalised windows prefix
            #[cfg(target_family = "windows")]
            let path = path
                .strip_prefix(r"\\?\")
                .map(|s| s.to_string())
                .unwrap_or(path);
            let line_numbers = module.line_numbers.clone();
            let source = ModuleSourceInformation { path, line_numbers };
            _ = self.sources.insert(name.clone(), source);
        }

        // Warnings from dependencies are not fixable by the programmer so
        // we don't bother them with diagnostics for them.
        let _ = self.take_warnings();

        // Compile the root package, that is, the one that the programmer is
        // working in.
        let (modules, error) = match self.project_compiler.compile_root_package() {
            Outcome::Ok(package) => (package.modules, None),
            Outcome::PartialFailure(package, error) => (package.modules, Some(error)),
            Outcome::TotalFailure(error) => (vec![], Some(error)),
        };

        // Record the compiled dependency modules
        let mut compiled_modules = compiled_dependencies
            .into_iter()
            .map(|m| m.input_path)
            .collect_vec();

        // Store the compiled module information
        for module in modules {
            let path = module.input_path.as_os_str().to_string_lossy().to_string();
            let line_numbers = LineNumbers::new(&module.code);
            let source = ModuleSourceInformation { path, line_numbers };
            // Record that this one has been compiled. This is returned by this
            // function and is used to determine what diagnostics to reset.
            compiled_modules.push(module.input_path.clone());
            // Register information for the LS to use
            _ = self.sources.insert(module.name.clone(), source);
            _ = self.modules.insert(module.name.clone(), module);
        }

        match error {
            None => Outcome::Ok(compiled_modules),
            Some(error) => Outcome::PartialFailure(compiled_modules, error),
        }
    }
}

impl<IO> LspProjectCompiler<IO> {
    pub fn take_warnings(&mut self) -> Vec<Warning> {
        self.warnings.take()
    }

    pub fn get_source(&self, module: &str) -> Option<&ModuleSourceInformation> {
        self.sources.get(module)
    }

    pub fn get_module_interface(&self, name: &str) -> Option<&ModuleInterface> {
        self.project_compiler.get_importable_modules().get(name)
    }
}

#[derive(Debug)]
pub struct ModuleSourceInformation {
    /// The path to the source file from within the project root
    pub path: String,

    /// Useful for converting from Gleam's byte index offsets to the LSP line
    /// and column number positions.
    pub line_numbers: LineNumbers,
}