//! Projects over the API (hub spec §8.2, §12.1): the same rules as the
//! pages, through the functions they use.

use super::{caller, forbidden, not_found, ApiError, Caller};
use crate::db::projects as pdb;
use crate::web::projects as wp;
use crate::Shared;
use axum::extract::{Path, Query, State};
use axum::http::{HeaderMap, StatusCode};
use axum::Json;
use hub_api::{
    Board, CardMove, CardsArchive, CardsArchived, CardsMove, CardsMoved, NewCard, NewProject, Project, ProjectCard, ProjectColumn,
    ProjectEdit,
};

fn project_of(app: &Shared, p: &pdb::Project) -> Project {
    Project {
        owner: p.owner.clone(),
        number: p.number,
        title: p.title.clone(),
        description: p.description.clone(),
        public: p.public,
        closed: p.closed,
        updated_ms: p.updated_ms,
        url: format!("{}/projects/{}/{}", app.config.base_url().trim_end_matches('/'), p.owner, p.number),
    }
}

fn card_of(v: &wp::CardView) -> ProjectCard {
    ProjectCard {
        id: v.card.id,
        kind: v.card.kind.clone(),
        reference: v.reference.clone(),
        title: v.title.clone(),
        state: v.state.clone(),
        labels: v.labels.iter().map(|l| l.name.clone()).collect(),
        assignees: v.assignees.clone(),
        archived_ms: v.card.archived_ms,
    }
}

async fn rights(app: &Shared, c: &Caller, owner: &str) -> Result<wp::Rights, ApiError> {
    wp::rights_of(app, c.account.as_ref(), owner).await?.ok_or_else(|| not_found("no such owner"))
}

/// A project the caller may see.
async fn visible(app: &Shared, c: &Caller, owner: &str, number: i64) -> Result<(wp::Rights, pdb::Project), ApiError> {
    let r = rights(app, c, owner).await?;
    let p = pdb::get(&app.db, owner, number).await?.filter(|p| p.public || r.member).ok_or_else(|| not_found("no such project"))?;
    Ok((r, p))
}

/// A project the caller may change: a write token, edit rights, and open unless `closed_ok`.
async fn changeable(
    app: &Shared,
    headers: &HeaderMap,
    owner: &str,
    number: i64,
    closed_ok: bool,
) -> Result<(Caller, pdb::Project), ApiError> {
    let c = caller(app, headers).await?;
    c.require("repo:write")?;
    let (r, p) = visible(app, &c, owner, number).await?;
    if !r.edit {
        return Err(forbidden("only the owner (or the organisation's members) may change this project"));
    }
    if p.closed && !closed_ok {
        return Err(ApiError(StatusCode::CONFLICT, "this project is closed; reopen it to change it".into()));
    }
    Ok((c, p))
}

/// A column by id or by name (case-insensitive); the first when absent.
async fn column(app: &Shared, project_id: i64, spec: Option<&str>) -> Result<pdb::Column, ApiError> {
    let cols = pdb::columns(&app.db, project_id).await?;
    let found = match spec.map(str::trim).filter(|s| !s.is_empty()) {
        None => cols.into_iter().next(),
        Some(s) => cols.into_iter().find(|c| c.id.to_string() == s || c.name.eq_ignore_ascii_case(s)),
    };
    found.ok_or_else(|| ApiError(StatusCode::BAD_REQUEST, "no such column".into()))
}

/// `GET /projects/{owner}`.
pub async fn list(State(app): State<Shared>, headers: HeaderMap, Path(owner): Path<String>) -> Result<Json<Vec<Project>>, ApiError> {
    let c = caller(&app, &headers).await?;
    let r = rights(&app, &c, &owner).await?;
    let list = pdb::of_owner(&app.db, &owner).await?;
    Ok(Json(list.iter().filter(|p| p.public || r.member).map(|p| project_of(&app, p)).collect()))
}

/// `POST /projects/{owner}`.
pub async fn create(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path(owner): Path<String>,
    Json(body): Json<NewProject>,
) -> Result<(StatusCode, Json<Project>), ApiError> {
    let c = caller(&app, &headers).await?;
    c.require("repo:write")?;
    if !rights(&app, &c, &owner).await?.edit {
        return Err(forbidden("only the owner (or the organisation's members) may create projects"));
    }
    let title = body.title.trim();
    if title.is_empty() || title.chars().count() > 100 {
        return Err(ApiError(StatusCode::BAD_REQUEST, "a project needs a title of up to 100 characters".into()));
    }
    let p = pdb::create(&app.db, &owner, title, body.description.trim(), !body.private).await?;
    crate::db::accounts::audit(&app.db, c.account.as_ref(), "project.created", &format!("{owner}/{}", p.number), title).await.ok();
    Ok((StatusCode::CREATED, Json(project_of(&app, &p))))
}

/// `GET /projects/{owner}/{n}`.
pub async fn board(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
) -> Result<Json<Board>, ApiError> {
    let c = caller(&app, &headers).await?;
    board_of(&app, &c, &owner, number).await
}

/// `PATCH /projects/{owner}/{n}`.
pub async fn edit(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Json(body): Json<ProjectEdit>,
) -> Result<Json<Project>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, true).await?;
    // A transfer (#125) first: the other fields then apply where it went.
    let (owner, number) = match body.owner.as_deref().map(str::trim).filter(|to| !to.is_empty() && *to != owner) {
        Some(to) => match wp::rights_of(&app, c.account.as_ref(), to).await? {
            Some(r) if r.edit => {
                let moved = pdb::transfer(&app.db, p.id, to).await?;
                let detail = format!("{owner}/{number} to {to}/{}", moved.number);
                crate::db::accounts::audit(&app.db, c.account.as_ref(), "project.transferred", &detail, &p.title).await.ok();
                (moved.owner, moved.number)
            }
            _ => return Err(ApiError(StatusCode::FORBIDDEN, format!("you cannot make projects under {to}"))),
        },
        None => (owner, number),
    };
    let p = pdb::get(&app.db, &owner, number).await?.unwrap_or(p);
    let title = body.title.as_deref().map(str::trim).filter(|t| !t.is_empty()).unwrap_or(&p.title).chars().take(100).collect::<String>();
    pdb::set(
        &app.db,
        p.id,
        &title,
        body.description.as_deref().map(str::trim).unwrap_or(&p.description),
        body.private.map(|x| !x).unwrap_or(p.public),
        body.closed.unwrap_or(p.closed),
    )
    .await?;
    let fresh = pdb::get(&app.db, &owner, number).await?.unwrap_or(p);
    Ok(Json(project_of(&app, &fresh)))
}

/// A board's columns as `GET /projects/{owner}/{n}` gives them, for the
/// column calls to answer with (#366).
async fn board_of(app: &Shared, c: &Caller, owner: &str, number: i64) -> Result<Json<Board>, ApiError> {
    let (_, p) = visible(app, c, owner, number).await?;
    let (columns, _) = wp::board_columns(app, c.account.as_ref(), owner, &p, false).await?;
    Ok(Json(Board {
        project: project_of(app, &p),
        columns: columns
            .iter()
            .map(|col| ProjectColumn { id: col.column.id, name: col.column.name.clone(), cards: col.cards.iter().map(card_of).collect() })
            .collect(),
    }))
}

/// A column's name: trimmed, 1 to 40 characters, as the board page has it.
fn column_name(name: &str) -> Result<&str, ApiError> {
    let name = name.trim();
    if name.is_empty() || name.chars().count() > 40 {
        return Err(ApiError(StatusCode::BAD_REQUEST, "a column has a name of 1 to 40 characters".into()));
    }
    Ok(name)
}

/// `POST /projects/{owner}/{n}/columns` (#366): add a column at the right;
/// answers the board.
pub async fn add_column(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Json(body): Json<hub_api::NewColumn>,
) -> Result<Json<Board>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let name = column_name(&body.name)?;
    if pdb::columns(&app.db, p.id).await?.iter().any(|col| col.name.eq_ignore_ascii_case(name)) {
        return Err(ApiError(StatusCode::CONFLICT, format!("the board has a column {name} already")));
    }
    pdb::add_column(&app.db, p.id, name).await?;
    board_of(&app, &c, &owner, number).await
}

/// `PATCH /projects/{owner}/{n}/columns/{column}` (#366): rename or move a
/// column named by id or name; answers the board.
pub async fn edit_column(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number, spec)): Path<(String, i64, String)>,
    Json(body): Json<hub_api::ColumnEdit>,
) -> Result<Json<Board>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let col = named_column(&app, p.id, &spec).await?;
    if body.name.is_none() && body.position.is_none() {
        return Err(ApiError(StatusCode::BAD_REQUEST, "say what to change: name or position".into()));
    }
    if let Some(name) = body.name.as_deref() {
        let name = column_name(name)?;
        let others = pdb::columns(&app.db, p.id).await?;
        if others.iter().any(|o| o.id != col.id && o.name.eq_ignore_ascii_case(name)) {
            return Err(ApiError(StatusCode::CONFLICT, format!("the board has a column {name} already")));
        }
        pdb::rename_column(&app.db, p.id, col.id, name).await?;
    }
    if let Some(pos) = body.position {
        pdb::place_column(&app.db, p.id, col.id, pos).await?;
    }
    board_of(&app, &c, &owner, number).await
}

/// `DELETE /projects/{owner}/{n}/columns/{column}` (#366): its cards go to
/// the first remaining column; a board keeps at least one. Answers the board.
pub async fn remove_column(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number, spec)): Path<(String, i64, String)>,
) -> Result<Json<Board>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let col = named_column(&app, p.id, &spec).await?;
    if !pdb::remove_column(&app.db, p.id, col.id).await? {
        return Err(ApiError(StatusCode::CONFLICT, "a board keeps at least one column".into()));
    }
    board_of(&app, &c, &owner, number).await
}

/// A column named by id or name, or 404.
async fn named_column(app: &Shared, project_id: i64, spec: &str) -> Result<pdb::Column, ApiError> {
    let cols = pdb::columns(&app.db, project_id).await?;
    cols.into_iter()
        .find(|c| c.id.to_string() == spec.trim() || c.name.eq_ignore_ascii_case(spec.trim()))
        .ok_or_else(|| ApiError(StatusCode::NOT_FOUND, format!("no column {spec}")))
}

/// `GET /projects/{owner}/{n}/cards`: the cards by column, as the board
/// has them.
#[derive(serde::Deserialize, Default)]
pub struct CardsQuery {
    /// The archived cards instead (#293).
    #[serde(default)]
    archived: bool,
}

/// `GET /projects/{owner}/{n}/cards`, `?archived=true` for the archived ones.
pub async fn cards(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Query(q): Query<CardsQuery>,
) -> Result<Json<Vec<ProjectColumn>>, ApiError> {
    if !q.archived {
        return Ok(Json(board(State(app), headers, Path((owner, number))).await?.0.columns));
    }
    let c = caller(&app, &headers).await?;
    let (_, p) = visible(&app, &c, &owner, number).await?;
    let (columns, _) = wp::board_columns(&app, c.account.as_ref(), &owner, &p, true).await?;
    Ok(Json(
        columns
            .iter()
            .map(|col| ProjectColumn { id: col.column.id, name: col.column.name.clone(), cards: col.cards.iter().map(card_of).collect() })
            .collect(),
    ))
}

/// `POST /projects/{owner}/{n}/cards`.
pub async fn add_card(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Json(body): Json<NewCard>,
) -> Result<(StatusCode, Json<ProjectCard>), ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let col = column(&app, p.id, body.column.as_deref()).await?;
    let actor = c.account.as_ref().map(|a| a.username.clone()).unwrap_or_default();
    let card = match wp::add_card(&app, c.account.as_ref(), &owner, p.id, col.id, &body.reference, "", &body.note, &actor).await? {
        Ok(card) => card,
        Err(why) => return Err(ApiError(StatusCode::BAD_REQUEST, why)),
    };
    // Answer with the card as the board shows it.
    let (columns, _) = wp::board_columns(&app, c.account.as_ref(), &owner, &p, false).await?;
    let view = columns
        .iter()
        .flat_map(|col| col.cards.iter())
        .find(|v| v.card.id == card.id)
        .map(card_of)
        .ok_or_else(|| not_found("no such card"))?;
    Ok((StatusCode::CREATED, Json(view)))
}

/// `PATCH /projects/{owner}/{n}/cards/{id}`: move to another column.
pub async fn move_card(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number, id)): Path<(String, i64, i64)>,
    Json(body): Json<CardMove>,
) -> Result<StatusCode, ApiError> {
    let (_, p) = changeable(&app, &headers, &owner, number, false).await?;
    let col = column(&app, p.id, Some(&body.column)).await?;
    if !pdb::cards(&app.db, p.id).await?.iter().any(|c| c.id == id) {
        return Err(not_found("no such card"));
    }
    pdb::move_card(&app.db, p.id, id, col.id).await?;
    Ok(StatusCode::NO_CONTENT)
}

/// Whether `card` is the one `name` names: its id, or its issue or
/// proposal as `12`, `#12`, `name#12` or `owner/name#12`.
fn names_card(name: &str, card: &ProjectCard) -> bool {
    let name = name.trim();
    if name.is_empty() {
        return false;
    }
    if name.parse::<i64>().is_ok_and(|id| id == card.id) {
        return true;
    }
    let Some((_, number)) = card.reference.rsplit_once('#') else { return false };
    match name.rsplit_once('#') {
        None => name == number,
        Some(("", n)) => n == number,
        Some((repo, n)) => n == number && (card.reference == format!("{repo}#{n}") || card.reference.ends_with(&format!("/{repo}#{n}"))),
    }
}

/// `POST /projects/{owner}/{n}/cards/move` (#289): a column's cards to
/// another at once, with exceptions and a state filter; one audit entry.
pub async fn move_cards(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Json(body): Json<CardsMove>,
) -> Result<Json<CardsMoved>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let from = column(&app, p.id, Some(&body.from)).await?;
    let to = column(&app, p.id, Some(&body.column)).await?;
    if from.id == to.id {
        return Err(ApiError(StatusCode::BAD_REQUEST, "the cards are in that column already".into()));
    }
    let (columns, _) = wp::board_columns(&app, c.account.as_ref(), &owner, &p, false).await?;
    let cards: Vec<ProjectCard> =
        columns.iter().filter(|col| col.column.id == from.id).flat_map(|col| col.cards.iter().map(card_of)).collect();
    let states: Vec<String> = body.state.iter().map(|s| s.trim().to_ascii_lowercase()).filter(|s| !s.is_empty()).collect();
    let (moved, kept): (Vec<ProjectCard>, Vec<ProjectCard>) = cards.into_iter().partition(|card| {
        !body.except.iter().any(|e| names_card(e, card)) && (states.is_empty() || states.iter().any(|s| card.state.eq_ignore_ascii_case(s)))
    });
    if !body.dry_run && !moved.is_empty() {
        let ids: Vec<i64> = moved.iter().map(|c| c.id).collect();
        pdb::move_cards(&app.db, p.id, &ids, to.id).await?;
        let detail = format!("{} card(s) from {} to {}", moved.len(), from.name, to.name);
        crate::db::accounts::audit(&app.db, c.account.as_ref(), "project.cards_moved", &format!("{owner}/{number}"), &detail).await.ok();
    }
    Ok(Json(CardsMoved { moved, kept, dry_run: body.dry_run }))
}

/// `POST /projects/{owner}/{n}/cards/archive` (#293): a column's cards off
/// the board at once, kept, with #289's exceptions and state filter and an
/// age; one audit entry.
pub async fn archive_cards(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number)): Path<(String, i64)>,
    Json(body): Json<CardsArchive>,
) -> Result<Json<CardsArchived>, ApiError> {
    let (c, p) = changeable(&app, &headers, &owner, number, false).await?;
    let from = column(&app, p.id, Some(&body.from)).await?;
    if body.older_days.is_some_and(|d| !(0..=3650).contains(&d)) {
        return Err(ApiError(StatusCode::BAD_REQUEST, "older_days is 0 to 3650".into()));
    }
    let (columns, _) = wp::board_columns(&app, c.account.as_ref(), &owner, &p, false).await?;
    let now = crate::db::now_ms();
    let states: Vec<String> = body.state.iter().map(|s| s.trim().to_ascii_lowercase()).filter(|s| !s.is_empty()).collect();
    let (archived, kept): (Vec<&wp::CardView>, Vec<&wp::CardView>) =
        columns.iter().filter(|col| col.column.id == from.id).flat_map(|col| col.cards.iter()).partition(|v| {
            let card = card_of(v);
            !body.except.iter().any(|e| names_card(e, &card))
                && (states.is_empty() || states.iter().any(|s| card.state.eq_ignore_ascii_case(s)))
                && body.older_days.is_none_or(|d| pdb::older_than(&v.card, d, now))
        });
    if !body.dry_run && !archived.is_empty() {
        let ids: Vec<i64> = archived.iter().map(|v| v.card.id).collect();
        pdb::archive_cards(&app.db, p.id, &ids).await?;
        let detail = format!("{} card(s) of {}", ids.len(), from.name);
        crate::db::accounts::audit(&app.db, c.account.as_ref(), "project.cards_archived", &format!("{owner}/{number}"), &detail).await.ok();
    }
    let stamp = |v: &wp::CardView| ProjectCard { archived_ms: (!body.dry_run).then_some(now), ..card_of(v) };
    Ok(Json(CardsArchived {
        archived: archived.into_iter().map(stamp).collect(),
        kept: kept.into_iter().map(card_of).collect(),
        dry_run: body.dry_run,
    }))
}

/// `POST /projects/{owner}/{n}/cards/{id}/restore` (#293): an archived
/// card back on the board, at the end of its column.
pub async fn restore_card(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number, id)): Path<(String, i64, i64)>,
) -> Result<StatusCode, ApiError> {
    let (_, p) = changeable(&app, &headers, &owner, number, false).await?;
    if !pdb::cards(&app.db, p.id).await?.iter().any(|c| c.id == id && c.archived_ms.is_some()) {
        return Err(not_found("no such archived card"));
    }
    pdb::restore_card(&app.db, p.id, id).await?;
    Ok(StatusCode::NO_CONTENT)
}

/// `DELETE /projects/{owner}/{n}/cards/{id}`.
pub async fn remove_card(
    State(app): State<Shared>,
    headers: HeaderMap,
    Path((owner, number, id)): Path<(String, i64, i64)>,
) -> Result<StatusCode, ApiError> {
    let (_, p) = changeable(&app, &headers, &owner, number, false).await?;
    if !pdb::cards(&app.db, p.id).await?.iter().any(|c| c.id == id) {
        return Err(not_found("no such card"));
    }
    pdb::remove_card(&app.db, p.id, id).await?;
    Ok(StatusCode::NO_CONTENT)
}