//! Which hub and repository a command talks to, and with which token.

//!

//! Inside an Oxygen checkout, `oh` uses the checkout's remote (`origin`, or

//! the only one, or `--remote NAME`): its URL names the hub and the

//! repository, and its token and CA are the ones `oxy` pushes with.

//! Elsewhere, `--repo OWNER/NAME` with the hub from `--hub`, `OH_HUB` or

//! the one `oh auth login` saved.

use anyhow::{anyhow, bail, Context, Result};

use serde::{Deserialize, Serialize};

use std::collections::BTreeMap;

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

/// `~/.config/oh/config.toml`: tokens and CAs by hub, and the default hub.

#[derive(Debug, Default, Serialize, Deserialize)]

pub struct Config {

    #[serde(default)]

    pub default_hub: Option<String>,

    #[serde(default)]

    pub hosts: BTreeMap<String, Host>,

}

#[derive(Clone, Debug, Default, Serialize, Deserialize)]

pub struct Host {

    pub token: String,

    #[serde(default)]

    pub ca: Option<PathBuf>,

}

pub fn config_path() -> Result<PathBuf> {

    if let Some(p) = std::env::var_os("OH_CONFIG") {

        return Ok(PathBuf::from(p));

    }

    let base = match std::env::var_os("XDG_CONFIG_HOME") {

        Some(d) => PathBuf::from(d),

        None => PathBuf::from(std::env::var_os("HOME").context("HOME is not set")?).join(".config"),

    };

    Ok(base.join("oh").join("config.toml"))

}

impl Config {

    pub fn load() -> Result<Config> {

        let p = config_path()?;

        match std::fs::read_to_string(&p) {

            Ok(t) => toml::from_str(&t).with_context(|| format!("parse {}", p.display())),

            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(Config::default()),

            Err(e) => Err(e).with_context(|| format!("read {}", p.display())),

        }

    }

    /// Written owner-only: it holds tokens.

    pub fn save(&self) -> Result<()> {

        use std::io::Write;

        use std::os::unix::fs::OpenOptionsExt;

        let p = config_path()?;

        std::fs::create_dir_all(p.parent().unwrap())?;

        let tmp = p.with_extension("toml.tmp");

        let mut f = std::fs::OpenOptions::new().write(true).create(true).truncate(true).mode(0o600).open(&tmp)?;

        f.write_all(toml::to_string_pretty(self)?.as_bytes())?;

        f.sync_all()?;

        std::fs::rename(&tmp, &p)?;

        Ok(())

    }

}

/// A hub, and a repository on it when the command needs one.

#[derive(Clone, Debug)]

pub struct Target {

    /// `https://host:port`, no trailing slash.

    pub hub: String,

    pub token: Option<String>,

    pub ca: Option<PathBuf>,

    pub owner: String,

    pub name: String,

}

impl Target {

    pub fn repo(&self) -> Result<(&str, &str)> {

        if self.owner.is_empty() {

            bail!("no repository: run inside an Oxygen checkout, or give --repo OWNER/NAME");

        }

        Ok((&self.owner, &self.name))

    }

    /// `/repos/{owner}/{name}`.

    pub fn repo_path(&self) -> Result<String> {

        let (o, n) = self.repo()?;

        Ok(format!("/repos/{o}/{n}"))

    }

}

/// Split `https://host:port/owner/name` into the hub and the repository.

pub fn split_url(url: &str) -> Result<(String, String, String)> {

    let (scheme, rest) = url.split_once("://").ok_or_else(|| anyhow!("{url} is not a hub URL"))?;

    let mut parts = rest.trim_end_matches('/').splitn(2, '/');

    let host = parts.next().unwrap_or("");

    let path = parts.next().unwrap_or("");

    let segs: Vec<&str> = path.split('/').filter(|s| !s.is_empty()).collect();

    match segs.as_slice() {

        [o, n] => Ok((format!("{scheme}://{host}"), o.to_string(), n.trim_end_matches(".oxy").to_string())),

        _ => bail!("{url} does not name a repository as https://hub/OWNER/NAME"),

    }

}

/// A token and CA for `hub` from the checkout at `dir` or one enclosing

/// it (a subrepo's parent): the first remote on that hub that has each.

fn checkout_credentials(dir: &Path, hub: &str) -> (Option<String>, Option<PathBuf>) {

    let (mut token, mut ca) = (None, None);

    let mut at = Some(dir.to_path_buf());

    while let Some(d) = at {

        let Ok(repo) = oxy_core::repo::Repo::open(&d) else { break };

        for (name, url) in &repo.config.remotes {

            if split_url(url).is_ok_and(|(h, _, _)| h.eq_ignore_ascii_case(hub)) {

                token = token.or_else(|| repo.config.remote_tokens.get(name).cloned());

                ca = ca.or_else(|| repo.config.remote_cas.get(name).map(PathBuf::from));

            }

        }

        if token.is_some() && ca.is_some() {

            break;

        }

        at = repo.root().parent().map(Path::to_path_buf);

    }

    (token, ca)

}

/// The hub of the checkout's remote (the one chosen, `origin`, or the only

/// one), for `--repo` without `--hub`.

fn checkout_hub(dir: &Path, remote: Option<&str>) -> Option<String> {

    let repo = oxy_core::repo::Repo::open(dir).ok()?;

    let remotes = &repo.config.remotes;

    let url = match remote {

        Some(n) => remotes.get(n)?,

        None => remotes.get("origin").or_else(|| (remotes.len() == 1).then(|| remotes.values().next()).flatten())?,

    };

    split_url(url).ok().map(|(hub, _, _)| hub)

}

pub struct Choice<'a> {

    pub repo: Option<&'a str>,

    pub hub: Option<&'a str>,

    pub remote: Option<&'a str>,

}

/// Resolve what to talk to from the flags, the checkout at `dir`, the

/// environment and the saved configuration.

pub fn resolve(choice: &Choice, dir: &Path, cfg: &Config) -> Result<Target> {

    let env_token = std::env::var("OH_TOKEN").ok().or_else(|| std::env::var("OXY_TOKEN").ok()).filter(|t| !t.is_empty());

    let env_ca = std::env::var_os("OXY_CA").map(PathBuf::from);

    let saved = |hub: &str| cfg.hosts.get(hub).cloned();

    if let Some(r) = choice.repo {

        let (owner, name) = r.split_once('/').ok_or_else(|| anyhow!("--repo takes OWNER/NAME"))?;

        // Inside a checkout, its remote's hub, token and CA serve for

        // another repository on the same hub.

        let hub = choice

            .hub

            .map(String::from)

            .or_else(|| std::env::var("OH_HUB").ok())

            .or_else(|| checkout_hub(dir, choice.remote))

            .or_else(|| cfg.default_hub.clone())

            .ok_or_else(|| anyhow!("which hub? give --hub URL, set OH_HUB, or run `oh auth login`"))?;

        let hub = hub.trim_end_matches('/').to_string();

        let host = saved(&hub).unwrap_or_default();

        let (co_token, co_ca) = checkout_credentials(dir, &hub);

        return Ok(Target {

            token: env_token.or(co_token).or(Some(host.token).filter(|t| !t.is_empty())),

            ca: env_ca.or(co_ca).or(host.ca),

            hub,

            owner: owner.into(),

            name: name.into(),

        });

    }

    // The checkout's remote.

    if let Ok(repo) = oxy_core::repo::Repo::open(dir) {

        let remotes = &repo.config.remotes;

        let name = match choice.remote {

            Some(n) => n.to_string(),

            None if remotes.contains_key("origin") => "origin".into(),

            None if remotes.len() == 1 => remotes.keys().next().unwrap().clone(),

            None if remotes.is_empty() => bail!("this checkout has no remote; give --repo OWNER/NAME"),

            None => bail!(

                "this checkout has several remotes ({}); choose one with --remote",

                remotes.keys().cloned().collect::<Vec<_>>().join(", ")

            ),

        };

        let url = remotes.get(&name).ok_or_else(|| anyhow!("no remote named {name}"))?;

        let (hub, owner, repo_name) = split_url(url)?;

        let host = saved(&hub).unwrap_or_default();

        // The remote's own, then a parent checkout's for the same hub (a

        // subrepo cloned before it recorded them), then the saved ones.

        let (up_token, up_ca) = repo.root().parent().map(|p| checkout_credentials(p, &hub)).unwrap_or_default();

        let token =

            env_token.or_else(|| repo.config.remote_tokens.get(&name).cloned()).or(up_token).or(Some(host.token).filter(|t| !t.is_empty()));

        let ca = env_ca.or_else(|| repo.config.remote_cas.get(&name).map(PathBuf::from)).or(up_ca).or(host.ca);

        return Ok(Target { hub, token, ca, owner, name: repo_name });

    }

    // No repository: commands that need only a hub.

    let hub = choice

        .hub

        .map(String::from)

        .or_else(|| std::env::var("OH_HUB").ok())

        .or_else(|| cfg.default_hub.clone())

        .ok_or_else(|| anyhow!("not in an Oxygen checkout: give --repo OWNER/NAME and --hub URL, or run `oh auth login`"))?;

    let hub = hub.trim_end_matches('/').to_string();

    let host = saved(&hub).unwrap_or_default();

    Ok(Target {

        token: env_token.or(Some(host.token).filter(|t| !t.is_empty())),

        ca: env_ca.or(host.ca),

        hub,

        owner: String::new(),

        name: String::new(),

    })

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn remote_urls_name_the_hub_and_the_repository() {

        assert_eq!(

            split_url("https://earth.example:7343/andy/oxygen").unwrap(),

            ("https://earth.example:7343".into(), "andy".into(), "oxygen".into())

        );

        assert_eq!(split_url("http://127.0.0.1:9/a/b/").unwrap().2, "b");

        assert!(split_url("https://hub/only-owner").is_err());

        assert!(split_url("not a url").is_err());

    }

    /// oxygenhub#50, #51: a subrepo checkout whose remote has no token

    /// borrows its parent's for the same hub, and --repo inside a checkout

    /// takes the checkout's hub and token.

    #[test]

    fn checkouts_lend_their_hub_and_token() {

        if std::env::var_os("OH_TOKEN").is_some() || std::env::var_os("OXY_TOKEN").is_some() || std::env::var_os("OH_HUB").is_some() {

            return;

        }

        let dir = tempfile::tempdir().unwrap();

        let parent = dir.path().join("metalgear");

        let mut p = oxy_core::repo::Repo::init(&parent).unwrap();

        p.config.set("remote.origin.url", "https://hub.example/doomsdayone/metalgear").unwrap();

        p.config.set("remote.origin.token", "parent-token").unwrap();

        p.save_config().unwrap();

        let sub = parent.join("rstar-api");

        let mut s = oxy_core::repo::Repo::init(&sub).unwrap();

        s.config.set("remote.origin.url", "https://hub.example/doomsdayone/rstar-api").unwrap();

        s.save_config().unwrap();

        let cfg = Config::default();

        let none = Choice { repo: None, hub: None, remote: None };

        let t = resolve(&none, &sub, &cfg).unwrap();

        assert_eq!((t.name.as_str(), t.token.as_deref()), ("rstar-api", Some("parent-token")));

        let other = Choice { repo: Some("doomsdayone/other"), hub: None, remote: None };

        let t = resolve(&other, &parent, &cfg).unwrap();

        assert_eq!((t.hub.as_str(), t.token.as_deref()), ("https://hub.example", Some("parent-token")));

    }

}