use ini::Ini;
use std::borrow::Cow;
use std::path::Path;
use std::path::PathBuf;
use std::sync::{LazyLock, OnceLock};

use super::{Context, Module, ModuleConfig};

use crate::configs::gcloud::GcloudConfig;
use crate::formatter::StringFormatter;
use crate::utils;

type Account<'a> = (&'a str, Option<&'a str>);

struct GcloudContext {
    config_name: String,
    config_path: PathBuf,
    config: OnceLock<Option<Ini>>,
}

impl<'a> GcloudContext {
    pub fn new(config_name: &str, config_path: &Path) -> Self {
        Self {
            config_name: config_name.to_string(),
            config_path: PathBuf::from(config_path),
            config: OnceLock::default(),
        }
    }

    fn get_config(&self) -> Option<&Ini> {
        self.config
            .get_or_init(|| Ini::load_from_file(&self.config_path).ok())
            .as_ref()
    }

    pub fn get_account(&'a self) -> Option<Account<'a>> {
        let config = self.get_config()?;
        let account = config.section(Some("core"))?.get("account")?;
        let mut segments = account.splitn(2, '@');
        Some((segments.next()?, segments.next()))
    }

    pub fn get_project(&'a self) -> Option<&'a str> {
        let config = self.get_config()?;
        config.section(Some("core"))?.get("project")
    }

    pub fn get_region(&'a self) -> Option<&'a str> {
        let config = self.get_config()?;
        config.section(Some("compute"))?.get("region")
    }
}

fn get_current_config(context: &Context) -> Option<(String, PathBuf)> {
    let config_dir = get_config_dir(context)?;
    let name = get_active_config(context, &config_dir)?;
    let path = config_dir
        .join("configurations")
        .join(format!("config_{name}"));
    Some((name, path))
}

fn get_config_dir(context: &Context) -> Option<PathBuf> {
    context
        .get_env("CLOUDSDK_CONFIG")
        .map(PathBuf::from)
        .or_else(|| {
            let home = context.get_home()?;
            Some(home.join(".config").join("gcloud"))
        })
}

fn get_active_config(context: &Context, config_dir: &Path) -> Option<String> {
    context.get_env("CLOUDSDK_ACTIVE_CONFIG_NAME").or_else(|| {
        let path = config_dir.join("active_config");
        utils::read_file(path)
            .ok()?
            .lines()
            .next()
            .map(String::from)
    })
}

pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
    let mut module = context.new_module("gcloud");
    let config: GcloudConfig = GcloudConfig::try_load(module.config);

    if !(context.detect_env_vars(&config.detect_env_vars)) {
        return None;
    }

    let (config_name, config_path) = get_current_config(context)?;

    if config_name == "NONE" {
        return None;
    }
    let gcloud_context = GcloudContext::new(&config_name, &config_path);
    let account: LazyLock<Option<Account<'_>>, _> = LazyLock::new(|| gcloud_context.get_account());

    let parsed = StringFormatter::new(config.format).and_then(|formatter| {
        formatter
            .map_meta(|variable, _| match variable {
                "symbol" => Some(config.symbol),
                _ => None,
            })
            .map_style(|variable| match variable {
                "style" => Some(Ok(config.style)),
                _ => None,
            })
            .map(|variable| match variable {
                "account" => account
                    .map(|(account, _)| account)
                    .map(Cow::Borrowed)
                    .map(Ok),
                "domain" => account
                    .and_then(|(_, domain)| domain)
                    .map(Cow::Borrowed)
                    .map(Ok),
                "region" => gcloud_context
                    .get_region()
                    .map(|region| config.region_aliases.get(region).copied().unwrap_or(region))
                    .map(Cow::Borrowed)
                    .map(Ok),
                "project" => context
                    .get_env("CLOUDSDK_CORE_PROJECT")
                    .map(Cow::Owned)
                    .or_else(|| gcloud_context.get_project().map(Cow::Borrowed))
                    .map(|project| {
                        config
                            .project_aliases
                            .get(project.as_ref())
                            .copied()
                            .map_or(project, Cow::Borrowed)
                    })
                    .map(Ok),
                "active" => Some(Ok(Cow::Borrowed(&gcloud_context.config_name))),
                _ => None,
            })
            .parse(None, Some(context))
    });

    module.set_segments(match parsed {
        Ok(segments) => segments,
        Err(error) => {
            log::error!("Error in module `gcloud`: \n{error}");
            return None;
        }
    });

    Some(module)
}

#[cfg(test)]
mod tests {
    use std::fs::{File, create_dir};
    use std::io::{self, Write};

    use nu_ansi_term::Color;

    use crate::test::ModuleRenderer;

    #[test]
    fn account_set_but_not_shown_because_of_detect_env_vars() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        // check if this config would lead to the module being rendered
        assert_eq!(
            ModuleRenderer::new("gcloud")
                .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
                .config(toml::toml! {
                    [gcloud]
                    format = "$active"
                })
                .collect(),
            Some("default".into())
        );

        // when we set `detect_env_vars` now, the module is empty
        assert_eq!(
            ModuleRenderer::new("gcloud")
                .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
                .config(toml::toml! {
                    [gcloud]
                    format = "$active"
                    detect_env_vars = ["SOME_TEST_VAR"]
                })
                .collect(),
            None
        );

        // and when the environment variable has a value, the module is shown
        assert_eq!(
            ModuleRenderer::new("gcloud")
                .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
                .env("SOME_TEST_VAR", "1")
                .config(toml::toml! {
                    [gcloud]
                    format = "$active"
                    detect_env_vars = ["SOME_TEST_VAR"]
                })
                .collect(),
            Some("default".into())
        );

        dir.close()
    }

    #[test]
    fn account_set() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
account = foo@example.com
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .collect();
        let expected = Some(format!(
            "on {} ",
            Color::Blue.bold().paint("☁️  foo@example.com")
        ));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn account_with_custom_format_set() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
account = foo@example.com
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$account(\\($region\\))]($style) "
            })
            .collect();
        let expected = Some(format!("on {} ", Color::Blue.bold().paint("☁️  foo")));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn account_and_region_set() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
account = foo@example.com

[compute]
region = us-central1
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .collect();
        let expected = Some(format!(
            "on {} ",
            Color::Blue.bold().paint("☁️  foo@example.com(us-central1)")
        ));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn account_and_region_set_with_alias() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
account = foo@example.com

[compute]
region = us-central1
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud.region_aliases]
                us-central1 = "uc1"
            })
            .collect();
        let expected = Some(format!(
            "on {} ",
            Color::Blue.bold().paint("☁️  foo@example.com(uc1)")
        ));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn active_set() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default1")?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$active]($style) "
            })
            .collect();
        let expected = Some(format!("on {} ", Color::Blue.bold().paint("☁️  default1")));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn project_set() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
project = abc
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$project]($style) "
            })
            .collect();
        let expected = Some(format!("on {} ", Color::Blue.bold().paint("☁️  abc")));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn project_set_in_env() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
project = abc
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CORE_PROJECT", "env_project")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$project]($style) "
            })
            .collect();
        let expected = Some(format!(
            "on {} ",
            Color::Blue.bold().paint("☁️  env_project")
        ));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn project_set_with_alias() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
project = very-long-project-name
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$project]($style) "
                [gcloud.project_aliases]
                very-long-project-name = "vlpn"
            })
            .collect();
        let expected = Some(format!("on {} ", Color::Blue.bold().paint("☁️  vlpn")));

        assert_eq!(actual, expected);
        dir.close()
    }

    #[test]
    fn region_not_set_with_display_region() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$region]($style) "
            })
            .collect();
        let expected = None;

        assert_eq!(expected, actual);
        dir.close()
    }

    #[test]
    fn no_active_config() {
        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_ACTIVE_CONFIG_NAME", "NONE")
            .collect();
        let expected = None;

        assert_eq!(expected, actual);
    }

    #[test]
    fn active_config_manually_overridden() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let active_config_path = dir.path().join("active_config");
        let mut active_config_file = File::create(active_config_path)?;
        active_config_file.write_all(b"default")?;

        create_dir(dir.path().join("configurations"))?;
        let config_default_path = dir.path().join("configurations").join("config_default");
        let mut config_default_file = File::create(config_default_path)?;
        config_default_file.write_all(
            b"\
[core]
project = default
",
        )?;

        let config_overridden_path = dir.path().join("configurations").join("config_overridden");
        let mut config_overridden_file = File::create(config_overridden_path)?;
        config_overridden_file.write_all(
            b"\
[core]
project = overridden
",
        )?;

        let actual = ModuleRenderer::new("gcloud")
            .env("CLOUDSDK_CONFIG", dir.path().to_string_lossy())
            .env("CLOUDSDK_ACTIVE_CONFIG_NAME", "overridden")
            .config(toml::toml! {
                [gcloud]
                format = "on [$symbol$project]($style) "
            })
            .collect();
        #[rustfmt::skip]
        let expected = Some(format!(
            "on {} ",
            Color::Blue.bold().paint("☁️  overridden")
        ));

        assert_eq!(actual, expected);
        dir.close()
    }
}
