use ini::Ini;
use std::path::Path;

use super::{Context, Module, RootModuleConfig};
use crate::configs::python::PythonConfig;
use crate::formatter::StringFormatter;
use crate::utils;

/// Creates a module with the current Python version
///
/// Will display the Python version if any of the following criteria are met:
///     - Current directory contains a `.python-version` file
///     - Current directory contains a `requirements.txt` file
///     - Current directory contains a `pyproject.toml` file
///     - Current directory contains a file with the `.py` extension
///     - Current directory contains a `Pipfile` file
///     - Current directory contains a `tox.ini` file
pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
    let mut module = context.new_module("python");
    let config: PythonConfig = PythonConfig::try_load(module.config);

    let is_py_project = {
        let base = context.try_begin_scan()?.set_files(&[
            "requirements.txt",
            ".python-version",
            "pyproject.toml",
            "Pipfile",
            "tox.ini",
            "setup.py",
            "__init__.py",
        ]);
        if config.scan_for_pyfiles {
            base.set_extensions(&["py"]).is_match()
        } else {
            base.is_match()
        }
    };

    let is_venv = context.get_env("VIRTUAL_ENV").is_some();

    if !is_py_project && !is_venv {
        return None;
    }

    let python_version = if config.pyenv_version_name {
        utils::exec_cmd("pyenv", &["version-name"])?.stdout
    } else {
        let version = get_python_version(&config.python_binary)?;
        format_python_version(&version)
    };
    let virtual_env = get_python_virtual_env(context);
    let pyenv_prefix = if config.pyenv_version_name {
        config.pyenv_prefix
    } else {
        ""
    };

    let parsed = StringFormatter::new(config.format).and_then(|formatter| {
        formatter
            .map_meta(|var, _| match var {
                "symbol" => Some(config.symbol),
                _ => None,
            })
            .map_style(|variable| match variable {
                "style" => Some(Ok(config.style)),
                _ => None,
            })
            .map(|variable| match variable {
                "version" => Some(Ok(python_version.trim())),
                "virtualenv" => virtual_env.as_ref().map(|e| Ok(e.trim())),
                "pyenv_prefix" => Some(Ok(pyenv_prefix)),
                _ => None,
            })
            .parse(None)
    });

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

    Some(module)
}

fn get_python_version(python_binary: &str) -> Option<String> {
    match utils::exec_cmd(python_binary, &["--version"]) {
        Some(output) => {
            if output.stdout.is_empty() {
                Some(output.stderr)
            } else {
                Some(output.stdout)
            }
        }
        None => None,
    }
}

fn format_python_version(python_stdout: &str) -> String {
    format!(
        "v{}",
        python_stdout
            .trim_start_matches("Python ")
            .trim_end_matches(":: Anaconda, Inc.")
            .trim()
    )
}

fn get_python_virtual_env(context: &Context) -> Option<String> {
    context.get_env("VIRTUAL_ENV").and_then(|venv| {
        get_prompt_from_venv(Path::new(&venv)).or_else(|| {
            Path::new(&venv)
                .file_name()
                .map(|filename| String::from(filename.to_str().unwrap_or("")))
        })
    })
}
fn get_prompt_from_venv(venv_path: &Path) -> Option<String> {
    Ini::load_from_file(venv_path.join("pyvenv.cfg"))
        .ok()?
        .general_section()
        .get("prompt")
        .map(String::from)
}

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

    #[test]
    fn test_format_python_version() {
        let input = "Python 3.7.2";
        assert_eq!(format_python_version(input), "v3.7.2");
    }

    #[test]
    fn test_format_python_version_anaconda() {
        let input = "Python 3.6.10 :: Anaconda, Inc.";
        assert_eq!(format_python_version(input), "v3.6.10");
    }

    #[test]
    fn folder_without_python_files() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        let actual = ModuleRenderer::new("python").path(dir.path()).collect();
        let expected = None;
        assert_eq!(expected, actual);

        dir.close()
    }

    #[test]
    fn folder_with_python_version() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join(".python-version"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_requirements_txt() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("requirements.txt"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_pyproject_toml() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("pyproject.toml"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_pipfile() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("Pipfile"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_tox() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("tox.ini"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_setup_py() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("setup.py"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_init_py() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("__init__.py"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn folder_with_py_file() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("main.py"))?.sync_all()?;

        check_python2_renders(&dir, None);
        check_python3_renders(&dir, None);
        check_pyenv_renders(&dir, None);
        dir.close()
    }

    #[test]
    fn disabled_scan_for_pyfiles_and_folder_with_ignored_py_file() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("foo.py"))?.sync_all()?;

        let expected = None;
        let config = toml::toml! {
            [python]
            scan_for_pyfiles = false
        };
        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .config(config)
            .collect();
        assert_eq!(expected, actual);
        dir.close()
    }

    #[test]
    fn disabled_scan_for_pyfiles_and_folder_with_setup_py() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("setup.py"))?.sync_all()?;

        let config = toml::toml! {
            [python]
            scan_for_pyfiles = false
        };

        check_python2_renders(&dir, Some(config));

        let config_python3 = toml::toml! {
            [python]
            python_binary = "python3"
            scan_for_pyfiles = false
        };

        check_python3_renders(&dir, Some(config_python3));

        let config_pyenv = toml::toml! {
            [python]
            pyenv_version_name = true
            pyenv_prefix = "test_pyenv "
            scan_for_pyfiles = false
        };
        check_pyenv_renders(&dir, Some(config_pyenv));
        dir.close()
    }

    #[test]
    fn with_virtual_env() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        File::create(dir.path().join("main.py"))?.sync_all()?;
        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .env("VIRTUAL_ENV", "/foo/bar/my_venv")
            .collect();

        let expected = Some(format!(
            "via {} ",
            Color::Yellow.bold().paint("🐍 v2.7.17 (my_venv)")
        ));

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

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

        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .env("VIRTUAL_ENV", "/foo/bar/my_venv")
            .collect();

        let expected = Some(format!(
            "via {} ",
            Color::Yellow.bold().paint("🐍 v2.7.17 (my_venv)")
        ));

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

    #[test]
    fn with_active_venv_and_prompt() -> io::Result<()> {
        let dir = tempfile::tempdir()?;
        create_dir_all(dir.path().join("my_venv"))?;
        let mut venv_cfg = File::create(dir.path().join("my_venv").join("pyvenv.cfg"))?;
        venv_cfg.write_all(
            br#"
home = something
prompt = 'foo' 
        "#,
        )?;
        venv_cfg.sync_all()?;

        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .env("VIRTUAL_ENV", dir.path().join("my_venv").to_str().unwrap())
            .collect();

        let expected = Some(format!(
            "via {} ",
            Color::Yellow.bold().paint("🐍 v2.7.17 (foo)")
        ));

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

    fn check_python2_renders(dir: &tempfile::TempDir, starship_config: Option<toml::Value>) {
        let config = starship_config.unwrap_or(toml::toml! {
            [python]
            python_binary = "python"
        });

        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .config(config)
            .collect();

        let expected = Some(format!("via {} ", Color::Yellow.bold().paint("🐍 v2.7.17")));
        assert_eq!(expected, actual);
    }

    fn check_python3_renders(dir: &tempfile::TempDir, starship_config: Option<toml::Value>) {
        let config = starship_config.unwrap_or(toml::toml! {
             [python]
             python_binary = "python3"
        });

        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .config(config)
            .collect();

        let expected = Some(format!("via {} ", Color::Yellow.bold().paint("🐍 v3.8.0")));
        assert_eq!(expected, actual);
    }

    fn check_pyenv_renders(dir: &tempfile::TempDir, starship_config: Option<toml::Value>) {
        let config = starship_config.unwrap_or(toml::toml! {
             [python]
             pyenv_version_name = true
             pyenv_prefix = "test_pyenv "
        });

        let actual = ModuleRenderer::new("python")
            .path(dir.path())
            .config(config)
            .collect();

        let expected = Some(format!(
            "via {} ",
            Color::Yellow.bold().paint("🐍 test_pyenv system")
        ));
        assert_eq!(expected, actual);
    }
}