//! `labels <number> [list|add|remove] [labels...]` — manage labels on
//! an issue or PR. Default action: list.

use anyhow::{Result, bail};
use clap::{Args as ClapArgs, Subcommand};
use forgejo_api::structs::{DeleteLabelsOption, IssueLabelsOption, IssueListLabelsQuery, Label};
use serde_json::json;

use crate::client::{Client, index};
use crate::verbs::print_json;

#[derive(ClapArgs)]
pub struct Args {
    /// Issue or PR number.
    pub(crate) number: u64,
    #[command(subcommand)]
    action: Option<Action>,
}

#[derive(Subcommand)]
enum Action {
    /// List labels (default when no action is given).
    List,
    /// Add labels by name.
    Add {
        /// Label names to add.
        labels: Vec<String>,
    },
    /// Remove labels by name.
    Remove {
        /// Label names to remove.
        labels: Vec<String>,
    },
}

pub fn run(client: &Client, args: Args) -> Result<()> {
    let (owner, name) = client.owner_repo()?;
    let idx = index(args.number)?;
    match args.action.unwrap_or(Action::List) {
        Action::List => {
            let labels = client.api().issue_get_labels(owner, name, idx).send()?;
            print_label_names(&labels);
        }
        Action::Add { labels } => {
            if labels.is_empty() {
                bail!("hive-forge labels add: pass at least one label name");
            }
            let all = repo_labels(client)?;
            let ids: Vec<serde_json::Value> = resolve_ids(&all, &labels)?
                .into_iter()
                .map(|id| json!(id))
                .collect();
            let resp = client
                .api()
                .issue_add_label(
                    owner,
                    name,
                    idx,
                    IssueLabelsOption {
                        labels: Some(ids),
                        updated_at: None,
                    },
                )
                .send()?;
            print_label_names(&resp);
        }
        Action::Remove { labels } => {
            if labels.is_empty() {
                bail!("hive-forge labels remove: pass at least one label name");
            }
            let all = repo_labels(client)?;
            for label in &labels {
                if let Some(id) = lookup_id(&all, label) {
                    let _ = client
                        .api()
                        .issue_remove_label(
                            owner,
                            name,
                            idx,
                            &id.to_string(),
                            DeleteLabelsOption { updated_at: None },
                        )
                        .send();
                }
            }
            let labels = client.api().issue_get_labels(owner, name, idx).send()?;
            print_label_names(&labels);
        }
    }
    Ok(())
}

/// The repo's whole label set, for name → id resolution. `pub(crate)` so
/// other verbs (`issue-create`, `pr-create`, `list`) can resolve a label
/// name without duplicating the lookup.
///
/// Paginated, where this used to ask for one page of 100 — **a page size
/// with no page loop is a lie the size of the page.** Truncation here is
/// worse than it looks: it doesn't drop a result, it makes a *valid*
/// label past the cut fail to resolve, and then prints an "available
/// labels" list that is itself incomplete, so the error argues for the
/// typo. Same root as the `list` trailer bug (assuming one request
/// returns the whole population), opposite direction — that one was a
/// false positive, this is a false negative.
pub(crate) fn repo_labels(client: &Client) -> Result<Vec<Label>> {
    /// Generous cap so a misbehaving server can't spin us forever.
    const MAX_PAGES: u32 = 50;
    const PAGE: u32 = 100;
    let (owner, name) = client.owner_repo()?;
    let mut all = Vec::new();
    for page in 1..=MAX_PAGES {
        let (_, batch) = client
            .api()
            .issue_list_labels(owner, name, IssueListLabelsQuery::default())
            .page(page)
            .page_size(PAGE)
            .send()?;
        let short = batch.len() < PAGE as usize;
        all.extend(batch);
        if short {
            break;
        }
    }
    Ok(all)
}

/// Resolve label names to ids, hard-erroring if any name doesn't match an
/// existing repo label. A typo used to silently produce fewer labels than
/// intended with no signal — not even a nonzero exit code — so callers
/// (`labels add`, `issue-create --label`, `pr-create --label`) had no way
/// to notice without manually diffing what they asked for against what
/// landed. The error lists both the exact names that didn't resolve and
/// every label actually available on the repo, so it's fixable from the
/// error alone without a second round-trip to `labels list`.
pub(crate) fn resolve_ids(all: &[Label], names: &[String]) -> Result<Vec<i64>> {
    let mut ids = Vec::with_capacity(names.len());
    let mut unresolved = Vec::new();
    for n in names {
        match lookup_id(all, n) {
            Some(id) => ids.push(id),
            None => unresolved.push(n.as_str()),
        }
    }
    if !unresolved.is_empty() {
        let available: Vec<&str> = all.iter().filter_map(|l| l.name.as_deref()).collect();
        bail!(
            "unresolved label name(s): {} — available labels: {}",
            crate::verbs::with_suggestions(&unresolved, &available),
            if available.is_empty() {
                "(none)".to_owned()
            } else {
                available.join(", ")
            }
        );
    }
    Ok(ids)
}

fn lookup_id(all: &[Label], name: &str) -> Option<i64> {
    all.iter()
        .find(|l| l.name.as_deref() == Some(name))
        .and_then(|l| l.id)
}

fn print_label_names(labels: &[Label]) {
    let names: Vec<&str> = labels.iter().filter_map(|l| l.name.as_deref()).collect();
    let _ = print_json(&json!(names));
}

#[cfg(test)]
mod tests {
    use super::resolve_ids;
    use forgejo_api::structs::Label;

    fn label(id: i64, name: &str) -> Label {
        Label {
            color: Some(String::new()),
            description: Some(String::new()),
            exclusive: None,
            id: Some(id),
            is_archived: None,
            name: Some(name.to_owned()),
            url: None,
        }
    }

    #[test]
    fn all_names_resolve_returns_ids_in_order() {
        let all = vec![label(1, "area/ops"), label(2, "type/bug")];
        let ids = resolve_ids(&all, &["type/bug".to_owned(), "area/ops".to_owned()]).unwrap();
        assert_eq!(ids, vec![2, 1]);
    }

    #[test]
    fn unresolved_name_errors_listing_the_typo_and_available_labels() {
        let all = vec![label(1, "area/ops"), label(2, "type/bug")];
        let err = resolve_ids(&all, &["area/op".to_owned()]).unwrap_err();
        let msg = err.to_string();
        assert!(msg.contains("area/op"), "missing typo'd name: {msg}");
        assert!(msg.contains("area/ops"), "missing available label: {msg}");
        assert!(msg.contains("type/bug"), "missing available label: {msg}");
    }

    #[test]
    fn unresolved_name_on_empty_repo_says_none_available() {
        let err = resolve_ids(&[], &["anything".to_owned()]).unwrap_err();
        assert!(err.to_string().contains("(none)"));
    }
}