use std::path::PathBuf;
use std::{env::current_dir, path::Path};

use anyhow::Context;
use clap::ValueEnum;
use comfy_table::Table;
use config::Config;
use serde::{Deserialize, Serialize};
use url::Url;

use crate::paths::berg_data_dir;

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
pub enum ConfigLocation {
    Global,
    Local,
}

/// Parsed configuration of the `berg` client
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BergConfig {
    /// base url for the forgejo instance that were going to talk to
    pub base_url: String,
    /// protocol used, typically only a choice between http/https
    pub protocol: String,
    /// the output of some actions is displayed in a table format.
    /// This can optionally be disabled to make the output more machine readable
    pub fancy_tables: bool,
    /// the output of some actions is displayed with extra colors in the terminal.
    /// This can optionally be disabled in case of e.g. color blindness
    ///
    /// WIP this does nothing yet since we don't have colors anyways yet
    pub no_color: bool,
}

impl BergConfig {
    fn iter_default_field_value() -> impl Iterator<Item = (&'static str, config::Value)> {
        let BergConfig {
            base_url,
            protocol,
            fancy_tables,
            no_color,
        } = Default::default();
        [
            ("base_url", config::Value::from(base_url)),
            ("protocol", config::Value::from(protocol)),
            ("fancy_tables", config::Value::from(fancy_tables)),
            ("no_color", config::Value::from(no_color)),
        ]
        .into_iter()
    }
}

impl Default for BergConfig {
    fn default() -> Self {
        Self {
            base_url: String::from("codeberg.org/"),
            protocol: String::from("https"),
            fancy_tables: true,
            no_color: false,
        }
    }
}

impl BergConfig {
    /// tries to read berg config from a known set of locations:
    ///
    /// The following list is ordered with descending priority
    ///
    /// - environment variables of the form "BERG_<config field name in caps>"
    /// - current directory + "berg.toml"
    /// - data dir + ".berg-cli/berg.toml""
    ///
    /// Note that config options are overridden with these priorities. This implies that if both
    /// global and local configs exist, all existing options from the local config override the
    /// global configs options. On the other hand, if some options are not overridden, then the
    /// global ones are used in this scenario.
    pub fn new() -> anyhow::Result<Self> {
        let config = Self::raw()?.try_deserialize::<BergConfig>()?;
        Ok(config)
    }

    pub fn raw() -> anyhow::Result<Config> {
        let local_config_path = current_dir().map(add_berg_config_file)?;
        let global_config_path = berg_data_dir().map(add_berg_config_file)?;
        let mut config_builder = Config::builder();

        // adding sources starting with least significant location
        //
        // - global
        // - local path uppermost parent
        // - local path walking down to pwd
        // - pwd
        // - env variable with BERG_ prefix

        config_builder = config_builder.add_source(file_from_path(global_config_path.as_path()));
        tracing::debug!("config search in: {global_config_path:?}");

        let mut walk_up = local_config_path.clone();
        let walking_up = std::iter::from_fn(move || {
            walk_up
                .parent()
                .and_then(|parent| parent.parent())
                .map(add_berg_config_file)
                .map(|parent| {
                    walk_up = parent.clone();
                    parent
                })
        });

        let pwd = std::iter::once(local_config_path);
        let local_paths = pwd.chain(walking_up).collect::<Vec<_>>();

        for path in local_paths.iter().rev() {
            tracing::debug!("config search in: {path:?}");
            config_builder = config_builder.add_source(file_from_path(path));
        }

        config_builder = config_builder.add_source(config::Environment::with_prefix("BERG"));
        // add default values if no source has the value set

        for (field_name, default_value) in BergConfig::iter_default_field_value() {
            config_builder = config_builder.set_default(field_name, default_value)?;
        }

        config_builder.build().map_err(anyhow::Error::from)
    }
}

impl BergConfig {
    pub fn url(&self) -> anyhow::Result<Url> {
        let url = format!(
            "{protoc}://{url}",
            protoc = self.protocol,
            url = self.base_url
        );
        Url::parse(url.as_str())
            .context("The protocol + base url in the config don't add up to a valid url")
    }

    pub fn make_table(&self) -> Table {
        let mut table = Table::new();

        let preset = if self.fancy_tables {
            comfy_table::presets::UTF8_FULL
        } else {
            // print everything on one line for long lines
            table.set_width(u16::MAX);
            comfy_table::presets::NOTHING
        };

        table.load_preset(preset);

        table
    }
}

fn file_from_path(
    path: impl AsRef<Path>,
) -> config::File<config::FileSourceFile, config::FileFormat> {
    config::File::new(
        path.as_ref().to_str().unwrap_or_default(),
        config::FileFormat::Toml,
    )
    .required(false)
}

fn add_berg_config_file(dir: impl AsRef<Path>) -> PathBuf {
    dir.as_ref().join("berg.toml")
}

#[cfg(test)]
mod tests {
    use super::*;

    fn make_config(path: PathBuf, config: BergConfig) -> anyhow::Result<()> {
        let config_path = add_berg_config_file(path);
        let toml = toml::to_string(&config)?;
        std::fs::write(config_path, toml)?;
        Ok(())
    }

    fn delete_config(path: PathBuf) -> anyhow::Result<()> {
        let config_path = add_berg_config_file(path);
        std::fs::remove_file(config_path)?;
        Ok(())
    }

    #[test]
    #[ignore = "doesn't work on nix in 'ci' because of no r/w permissions on the system"]
    fn berg_config_integration_test() -> anyhow::Result<()> {
        // ensure the directories are there while testing
        // (otherwise CI will fail)
        let local_dir = current_dir()?;
        std::fs::create_dir_all(local_dir)?;
        let global_dir = berg_data_dir()?;
        std::fs::create_dir_all(global_dir)?;

        // test local config
        let config = BergConfig {
            base_url: String::from("local"),
            ..Default::default()
        };
        make_config(current_dir()?, config)?;
        let config = BergConfig::new();
        assert!(config.is_ok(), "{config:?}");
        let config = config.unwrap();
        assert_eq!(config.base_url.as_str(), "local");
        delete_config(current_dir()?)?;

        // test global config
        let config = BergConfig {
            base_url: String::from("global"),
            ..Default::default()
        };
        make_config(berg_data_dir()?, config)?;
        let config = BergConfig::new();
        assert!(config.is_ok(), "{config:?}");
        let config = config.unwrap();
        assert_eq!(config.base_url.as_str(), "global");
        delete_config(berg_data_dir()?)?;

        // test creating template global config works
        let config = BergConfig::new();
        assert!(config.is_ok(), "{config:?}");
        let config = config.unwrap();
        assert_eq!(config.base_url.as_str(), "codeberg.org/");

        // testing behavior if both configs exist
        {
            // local
            let config = BergConfig {
                base_url: String::from("local"),
                ..Default::default()
            };
            make_config(current_dir()?, config)?;
        }
        {
            // global
            let config = BergConfig {
                base_url: String::from("global"),
                ..Default::default()
            };
            make_config(berg_data_dir()?, config)?;
        }
        let config = BergConfig::new();
        assert!(config.is_ok(), "{config:?}");
        let config = config.unwrap();
        assert_eq!(config.base_url.as_str(), "local");
        delete_config(current_dir()?)?;
        delete_config(berg_data_dir()?)?;

        Ok(())
    }
}