use yaml_rust::YamlLoader;

use std::borrow::Cow;
use std::env;
use std::path;

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

use crate::configs::kubernetes::KubernetesConfig;
use crate::formatter::StringFormatter;
use crate::utils;

struct KubeCtxComponents {
    user: Option<String>,
    namespace: Option<String>,
    cluster: Option<String>,
}

fn get_kube_context(filename: path::PathBuf) -> Option<String> {
    let contents = utils::read_file(filename).ok()?;

    let yaml_docs = YamlLoader::load_from_str(&contents).ok()?;
    if yaml_docs.is_empty() {
        return None;
    }
    let conf = &yaml_docs[0];

    let current_ctx = conf["current-context"].as_str()?;

    if current_ctx.is_empty() {
        return None;
    }
    Some(current_ctx.to_string())
}

fn get_kube_ctx_component(
    filename: path::PathBuf,
    current_ctx: String,
) -> Option<KubeCtxComponents> {
    let contents = utils::read_file(filename).ok()?;

    let yaml_docs = YamlLoader::load_from_str(&contents).ok()?;
    if yaml_docs.is_empty() {
        return None;
    }
    let conf = &yaml_docs[0];

    let ctx_yaml = conf["contexts"].as_vec().and_then(|contexts| {
        contexts
            .iter()
            .filter_map(|ctx| Some((ctx, ctx["name"].as_str()?)))
            .find(|(_, name)| *name == current_ctx)
    });

    let ctx_components = KubeCtxComponents {
        user: ctx_yaml
            .and_then(|(ctx, _)| ctx["context"]["user"].as_str())
            .and_then(|s| {
                if s.is_empty() {
                    return None;
                }
                Some(s.to_owned())
            }),
        namespace: ctx_yaml
            .and_then(|(ctx, _)| ctx["context"]["namespace"].as_str())
            .and_then(|s| {
                if s.is_empty() {
                    return None;
                }
                Some(s.to_owned())
            }),
        cluster: ctx_yaml
            .and_then(|(ctx, _)| ctx["context"]["cluster"].as_str())
            .and_then(|s| {
                if s.is_empty() {
                    return None;
                }
                Some(s.to_owned())
            }),
    };

    Some(ctx_components)
}

fn get_kube_context_name<'a>(config: &'a KubernetesConfig, kube_ctx: &'a str) -> Cow<'a, str> {
    if let Some(val) = config.context_aliases.get(kube_ctx) {
        return Cow::Borrowed(val);
    }

    config
        .context_aliases
        .iter()
        .find_map(|(k, v)| {
            let re = regex::Regex::new(&format!("^{}$", k)).ok()?;
            match re.replace(kube_ctx, *v) {
                Cow::Owned(replaced) => Some(Cow::Owned(replaced)),
                _ => None,
            }
        })
        .unwrap_or(Cow::Borrowed(kube_ctx))
}

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

    // As we default to disabled=true, we have to check here after loading our config module,
    // before it was only checking against whatever is in the config starship.toml
    if config.disabled {
        return None;
    };

    let default_config_file = context.get_home()?.join(".kube").join("config");

    let kube_cfg = context
        .get_env("KUBECONFIG")
        .unwrap_or(default_config_file.to_str()?.to_string());

    let kube_ctx = env::split_paths(&kube_cfg).find_map(get_kube_context)?;

    let ctx_components: Vec<Option<KubeCtxComponents>> = env::split_paths(&kube_cfg)
        .map(|filename| get_kube_ctx_component(filename, kube_ctx.clone()))
        .collect();

    let kube_user = ctx_components.iter().find(|&ctx| match ctx {
        Some(kube) => kube.user.is_some(),
        None => false,
    });
    let kube_ns = ctx_components.iter().find(|&ctx| match ctx {
        Some(kube) => kube.namespace.is_some(),
        None => false,
    });
    let kube_cluster = ctx_components.iter().find(|&ctx| match ctx {
        Some(kube) => kube.cluster.is_some(),
        None => false,
    });

    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 {
                "context" => Some(Ok(get_kube_context_name(&config, &kube_ctx))),

                "namespace" => kube_ns.and_then(|ctx| {
                    ctx.as_ref().map(|kube| {
                        // unwrap is safe as kube_ns only holds kube.namespace.is_some()
                        Ok(Cow::Borrowed(kube.namespace.as_ref().unwrap().as_str()))
                    })
                }),
                "user" => kube_user.and_then(|ctx| {
                    ctx.as_ref().map(|kube| {
                        // unwrap is safe as kube_user only holds kube.user.is_some()
                        Ok(Cow::Borrowed(kube.user.as_ref().unwrap().as_str()))
                    })
                }),
                "cluster" => kube_cluster.and_then(|ctx| {
                    ctx.as_ref().map(|kube| {
                        // unwrap is safe as kube_cluster only holds kube.cluster.is_some()
                        Ok(Cow::Borrowed(kube.cluster.as_ref().unwrap().as_str()))
                    })
                }),

                _ => None,
            })
            .parse(None, Some(context))
    });

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

    Some(module)
}

#[cfg(test)]
mod tests {
    use crate::test::ModuleRenderer;
    use ansi_term::Color;
    use std::env;
    use std::fs::File;
    use std::io::{self, Write};

    #[test]
    fn test_none_when_disabled() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .collect();

        assert_eq!(None, actual);

        dir.close()
    }

    fn base_test_ctx_alias(ctx_name: &str, config: toml::Value, expected: &str) -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            format!(
                "
apiVersion: v1
clusters: []
contexts: []
current-context: {}
kind: Config
preferences: {{}}
users: []
",
                ctx_name
            )
            .as_bytes(),
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(config)
            .collect();

        let expected = Some(format!("{} in ", Color::Cyan.bold().paint(expected)));
        assert_eq!(expected, actual);

        dir.close()
    }

    #[test]
    fn test_ctx_alias_simple() -> io::Result<()> {
        base_test_ctx_alias(
            "test_context",
            toml::toml! {
                [kubernetes]
                disabled = false
                [kubernetes.context_aliases]
                "test_context" = "test_alias"
                ".*" = "literal match has precedence"
            },
            "☸ test_alias",
        )
    }

    #[test]
    fn test_ctx_alias_regex() -> io::Result<()> {
        base_test_ctx_alias(
            "namespace/openshift-cluster/user",
            toml::toml! {
                [kubernetes]
                disabled = false
                [kubernetes.context_aliases]
                ".*/openshift-cluster/.*" = "test_alias"
            },
            "☸ test_alias",
        )
    }

    #[test]
    fn test_ctx_alias_regex_replace() -> io::Result<()> {
        base_test_ctx_alias(
            "gke_infra-cluster-28cccff6_europe-west4_cluster-1",
            toml::toml! {
                [kubernetes]
                disabled = false
                [kubernetes.context_aliases]
                "gke_.*_(?P<cluster>[\\w-]+)" = "example: $cluster"
            },
            "☸ example: cluster-1",
        )
    }

    #[test]
    fn test_ctx_alias_broken_regex() -> io::Result<()> {
        base_test_ctx_alias(
            "input",
            toml::toml! {
                [kubernetes]
                disabled = false
                [kubernetes.context_aliases]
                "input[.*" = "this does not match"
            },
            "☸ input",
        )
    }

    #[test]
    fn test_single_config_file_no_ns() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                disabled = false
            })
            .collect();

        let expected = Some(format!(
            "{} in ",
            Color::Cyan.bold().paint("☸ test_context")
        ));
        assert_eq!(expected, actual);

        dir.close()
    }

    #[test]
    fn test_single_config_file_with_ns() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                disabled = false
            })
            .collect();

        let expected = Some(format!(
            "{} in ",
            Color::Cyan.bold().paint("☸ test_context (test_namespace)")
        ));
        assert_eq!(expected, actual);

        dir.close()
    }

    #[test]
    fn test_single_config_file_with_multiple_ctxs() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: another_cluster
      user: another_user
      namespace: another_namespace
    name: another_context
  - context:
      cluster: test_cluster
      user: test_user
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                disabled = false
            })
            .collect();

        let expected = Some(format!(
            "{} in ",
            Color::Cyan.bold().paint("☸ test_context (test_namespace)")
        ));
        assert_eq!(expected, actual);

        dir.close()
    }

    #[test]
    fn test_multiple_config_files_with_ns() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename_cc = dir.path().join("config_cc");

        let mut file_cc = File::create(&filename_cc)?;
        file_cc.write_all(
            b"
apiVersion: v1
clusters: []
contexts: []
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file_cc.sync_all()?;

        let filename_ctx = dir.path().join("config_ctx");
        let mut file_ctx = File::create(&filename_ctx)?;
        file_ctx.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
      namespace: test_namespace
    name: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file_ctx.sync_all()?;

        // Test current_context first
        let actual_cc_first = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env(
                "KUBECONFIG",
                env::join_paths([&filename_cc, &filename_ctx])
                    .unwrap()
                    .to_string_lossy(),
            )
            .config(toml::toml! {
                [kubernetes]
                disabled = false
            })
            .collect();

        // And tes with context and namespace first
        let actual_ctx_first = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env(
                "KUBECONFIG",
                env::join_paths([&filename_ctx, &filename_cc])
                    .unwrap()
                    .to_string_lossy(),
            )
            .config(toml::toml! {
                [kubernetes]
                disabled = false
            })
            .collect();

        let expected = Some(format!(
            "{} in ",
            Color::Cyan.bold().paint("☸ test_context (test_namespace)")
        ));
        assert_eq!(expected, actual_cc_first);
        assert_eq!(expected, actual_ctx_first);

        dir.close()
    }

    #[test]
    fn test_kube_user() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                format = "($user)"
                disabled = false
            })
            .collect();

        let expected = Some("test_user".to_string());
        assert_eq!(expected, actual);
        dir.close()
    }

    #[test]
    fn test_kube_cluster() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      user: test_user
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                format = "($cluster)"
                disabled = false
            })
            .collect();

        let expected = Some("test_cluster".to_string());
        assert_eq!(expected, actual);
        dir.close()
    }

    #[test]
    fn test_kube_user_missing() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      cluster: test_cluster
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                format = "$symbol($user )($cluster )($namespace)"
                disabled = false
            })
            .collect();

        let expected = Some("☸ test_cluster test_namespace".to_string());
        assert_eq!(expected, actual);
        dir.close()
    }

    #[test]
    fn test_kube_cluster_missing() -> io::Result<()> {
        let dir = tempfile::tempdir()?;

        let filename = dir.path().join("config");

        let mut file = File::create(&filename)?;
        file.write_all(
            b"
apiVersion: v1
clusters: []
contexts:
  - context:
      user: test_user
      namespace: test_namespace
    name: test_context
current-context: test_context
kind: Config
preferences: {}
users: []
",
        )?;
        file.sync_all()?;

        let actual = ModuleRenderer::new("kubernetes")
            .path(dir.path())
            .env("KUBECONFIG", filename.to_string_lossy().as_ref())
            .config(toml::toml! {
                [kubernetes]
                format = "$symbol($user )($cluster )($namespace)"
                disabled = false
            })
            .collect();

        let expected = Some("☸ test_user test_namespace".to_string());
        assert_eq!(expected, actual);
        dir.close()
    }
}
