use anyhow::{anyhow, bail, Context, Result};
use async_trait::async_trait;
use futures::StreamExt;
use gpui::AsyncApp;
use http_client::github::{latest_github_release, GitHubLspBinaryVersion};
pub use language::*;
use lsp::{InitializeParams, LanguageServerBinary, LanguageServerName};
use serde_json::json;
use smol::fs::{self, File};
use std::{any::Any, env::consts, path::PathBuf, sync::Arc};
use util::{fs::remove_matching, maybe, merge_json_value_into, ResultExt};

pub struct CLspAdapter;

impl CLspAdapter {
    const SERVER_NAME: LanguageServerName = LanguageServerName::new_static("clangd");
}

#[async_trait(?Send)]
impl super::LspAdapter for CLspAdapter {
    fn name(&self) -> LanguageServerName {
        Self::SERVER_NAME.clone()
    }

    async fn check_if_user_installed(
        &self,
        delegate: &dyn LspAdapterDelegate,
        _: Arc<dyn LanguageToolchainStore>,
        _: &AsyncApp,
    ) -> Option<LanguageServerBinary> {
        let path = delegate.which(Self::SERVER_NAME.as_ref()).await?;
        Some(LanguageServerBinary {
            path,
            arguments: vec![],
            env: None,
        })
    }

    async fn fetch_latest_server_version(
        &self,
        delegate: &dyn LspAdapterDelegate,
    ) -> Result<Box<dyn 'static + Send + Any>> {
        let release =
            latest_github_release("clangd/clangd", true, false, delegate.http_client()).await?;
        let os_suffix = match consts::OS {
            "macos" => "mac",
            "linux" => "linux",
            "windows" => "windows",
            other => bail!("Running on unsupported os: {other}"),
        };
        let asset_name = format!("clangd-{}-{}.zip", os_suffix, release.tag_name);
        let asset = release
            .assets
            .iter()
            .find(|asset| asset.name == asset_name)
            .ok_or_else(|| anyhow!("no asset found matching {:?}", asset_name))?;
        let version = GitHubLspBinaryVersion {
            name: release.tag_name,
            url: asset.browser_download_url.clone(),
        };
        Ok(Box::new(version) as Box<_>)
    }

    async fn fetch_server_binary(
        &self,
        version: Box<dyn 'static + Send + Any>,
        container_dir: PathBuf,
        delegate: &dyn LspAdapterDelegate,
    ) -> Result<LanguageServerBinary> {
        let version = version.downcast::<GitHubLspBinaryVersion>().unwrap();
        let zip_path = container_dir.join(format!("clangd_{}.zip", version.name));
        let version_dir = container_dir.join(format!("clangd_{}", version.name));
        let binary_path = version_dir.join("bin/clangd");

        if fs::metadata(&binary_path).await.is_err() {
            let mut response = delegate
                .http_client()
                .get(&version.url, Default::default(), true)
                .await
                .context("error downloading release")?;
            let mut file = File::create(&zip_path).await?;
            if !response.status().is_success() {
                Err(anyhow!(
                    "download failed with status {}",
                    response.status().to_string()
                ))?;
            }
            futures::io::copy(response.body_mut(), &mut file).await?;

            let unzip_status = util::command::new_smol_command("unzip")
                .current_dir(&container_dir)
                .arg(&zip_path)
                .output()
                .await?
                .status;
            if !unzip_status.success() {
                Err(anyhow!("failed to unzip clangd archive"))?;
            }

            remove_matching(&container_dir, |entry| entry != version_dir).await;
        }

        Ok(LanguageServerBinary {
            path: binary_path,
            env: None,
            arguments: vec![],
        })
    }

    async fn cached_server_binary(
        &self,
        container_dir: PathBuf,
        _: &dyn LspAdapterDelegate,
    ) -> Option<LanguageServerBinary> {
        get_cached_server_binary(container_dir).await
    }

    async fn label_for_completion(
        &self,
        completion: &lsp::CompletionItem,
        language: &Arc<Language>,
    ) -> Option<CodeLabel> {
        let label_detail = match &completion.label_details {
            Some(label_detail) => match &label_detail.detail {
                Some(detail) => detail.trim(),
                None => "",
            },
            None => "",
        };

        let label = completion
            .label
            .strip_prefix('•')
            .unwrap_or(&completion.label)
            .trim()
            .to_owned()
            + label_detail;

        match completion.kind {
            Some(lsp::CompletionItemKind::FIELD) if completion.detail.is_some() => {
                let detail = completion.detail.as_ref().unwrap();
                let text = format!("{} {}", detail, label);
                let source = Rope::from(format!("struct S {{ {} }}", text).as_str());
                let runs = language.highlight_text(&source, 11..11 + text.len());
                return Some(CodeLabel {
                    filter_range: detail.len() + 1..text.len(),
                    text,
                    runs,
                });
            }
            Some(lsp::CompletionItemKind::CONSTANT | lsp::CompletionItemKind::VARIABLE)
                if completion.detail.is_some() =>
            {
                let detail = completion.detail.as_ref().unwrap();
                let text = format!("{} {}", detail, label);
                let runs = language.highlight_text(&Rope::from(text.as_str()), 0..text.len());
                return Some(CodeLabel {
                    filter_range: detail.len() + 1..text.len(),
                    text,
                    runs,
                });
            }
            Some(lsp::CompletionItemKind::FUNCTION | lsp::CompletionItemKind::METHOD)
                if completion.detail.is_some() =>
            {
                let detail = completion.detail.as_ref().unwrap();
                let text = format!("{} {}", detail, label);
                let runs = language.highlight_text(&Rope::from(text.as_str()), 0..text.len());
                let filter_start = detail.len() + 1;
                let filter_end =
                    if let Some(end) = text.rfind('(').filter(|end| *end > filter_start) {
                        end
                    } else {
                        text.len()
                    };

                return Some(CodeLabel {
                    filter_range: filter_start..filter_end,
                    text,
                    runs,
                });
            }
            Some(kind) => {
                let highlight_name = match kind {
                    lsp::CompletionItemKind::STRUCT
                    | lsp::CompletionItemKind::INTERFACE
                    | lsp::CompletionItemKind::CLASS
                    | lsp::CompletionItemKind::ENUM => Some("type"),
                    lsp::CompletionItemKind::ENUM_MEMBER => Some("variant"),
                    lsp::CompletionItemKind::KEYWORD => Some("keyword"),
                    lsp::CompletionItemKind::VALUE | lsp::CompletionItemKind::CONSTANT => {
                        Some("constant")
                    }
                    _ => None,
                };
                if let Some(highlight_id) = language
                    .grammar()
                    .and_then(|g| g.highlight_id_for_name(highlight_name?))
                {
                    let mut label = CodeLabel::plain(label.to_string(), None);
                    label.runs.push((
                        0..label.text.rfind('(').unwrap_or(label.text.len()),
                        highlight_id,
                    ));
                    return Some(label);
                }
            }
            _ => {}
        }
        Some(CodeLabel::plain(label.to_string(), None))
    }

    async fn label_for_symbol(
        &self,
        name: &str,
        kind: lsp::SymbolKind,
        language: &Arc<Language>,
    ) -> Option<CodeLabel> {
        let (text, filter_range, display_range) = match kind {
            lsp::SymbolKind::METHOD | lsp::SymbolKind::FUNCTION => {
                let text = format!("void {} () {{}}", name);
                let filter_range = 0..name.len();
                let display_range = 5..5 + name.len();
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::STRUCT => {
                let text = format!("struct {} {{}}", name);
                let filter_range = 7..7 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::ENUM => {
                let text = format!("enum {} {{}}", name);
                let filter_range = 5..5 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::INTERFACE | lsp::SymbolKind::CLASS => {
                let text = format!("class {} {{}}", name);
                let filter_range = 6..6 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::CONSTANT => {
                let text = format!("const int {} = 0;", name);
                let filter_range = 10..10 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::MODULE => {
                let text = format!("namespace {} {{}}", name);
                let filter_range = 10..10 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            lsp::SymbolKind::TYPE_PARAMETER => {
                let text = format!("typename {} {{}};", name);
                let filter_range = 9..9 + name.len();
                let display_range = 0..filter_range.end;
                (text, filter_range, display_range)
            }
            _ => return None,
        };

        Some(CodeLabel {
            runs: language.highlight_text(&text.as_str().into(), display_range.clone()),
            text: text[display_range].to_string(),
            filter_range,
        })
    }

    fn prepare_initialize_params(
        &self,
        mut original: InitializeParams,
    ) -> Result<InitializeParams> {
        // enable clangd's dot-to-arrow feature.
        let experimental = json!({
            "textDocument": {
                "completion" : {
                    "editsNearCursor": true
                },
                "inactiveRegionsCapabilities": {
                    "inactiveRegions": true,
                }
            }
        });
        if let Some(ref mut original_experimental) = original.capabilities.experimental {
            merge_json_value_into(experimental, original_experimental);
        } else {
            original.capabilities.experimental = Some(experimental);
        }
        Ok(original)
    }
}

async fn get_cached_server_binary(container_dir: PathBuf) -> Option<LanguageServerBinary> {
    maybe!(async {
        let mut last_clangd_dir = None;
        let mut entries = fs::read_dir(&container_dir).await?;
        while let Some(entry) = entries.next().await {
            let entry = entry?;
            if entry.file_type().await?.is_dir() {
                last_clangd_dir = Some(entry.path());
            }
        }
        let clangd_dir = last_clangd_dir.ok_or_else(|| anyhow!("no cached binary"))?;
        let clangd_bin = clangd_dir.join("bin/clangd");
        if clangd_bin.exists() {
            Ok(LanguageServerBinary {
                path: clangd_bin,
                env: None,
                arguments: vec![],
            })
        } else {
            Err(anyhow!(
                "missing clangd binary in directory {:?}",
                clangd_dir
            ))
        }
    })
    .await
    .log_err()
}

#[cfg(test)]
mod tests {
    use gpui::{AppContext as _, BorrowAppContext, TestAppContext};
    use language::{language_settings::AllLanguageSettings, AutoindentMode, Buffer};
    use settings::SettingsStore;
    use std::num::NonZeroU32;

    #[gpui::test]
    async fn test_c_autoindent(cx: &mut TestAppContext) {
        // cx.executor().set_block_on_ticks(usize::MAX..=usize::MAX);
        cx.update(|cx| {
            let test_settings = SettingsStore::test(cx);
            cx.set_global(test_settings);
            language::init(cx);
            cx.update_global::<SettingsStore, _>(|store, cx| {
                store.update_user_settings::<AllLanguageSettings>(cx, |s| {
                    s.defaults.tab_size = NonZeroU32::new(2);
                });
            });
        });
        let language = crate::language("c", tree_sitter_c::LANGUAGE.into());

        cx.new(|cx| {
            let mut buffer = Buffer::local("", cx).with_language(language, cx);

            // empty function
            buffer.edit([(0..0, "int main() {}")], None, cx);

            // indent inside braces
            let ix = buffer.len() - 1;
            buffer.edit([(ix..ix, "\n\n")], Some(AutoindentMode::EachLine), cx);
            assert_eq!(buffer.text(), "int main() {\n  \n}");

            // indent body of single-statement if statement
            let ix = buffer.len() - 2;
            buffer.edit([(ix..ix, "if (a)\nb;")], Some(AutoindentMode::EachLine), cx);
            assert_eq!(buffer.text(), "int main() {\n  if (a)\n    b;\n}");

            // indent inside field expression
            let ix = buffer.len() - 3;
            buffer.edit([(ix..ix, "\n.c")], Some(AutoindentMode::EachLine), cx);
            assert_eq!(buffer.text(), "int main() {\n  if (a)\n    b\n      .c;\n}");

            buffer
        });
    }
}
