//! Admin endpoints for routes. Mounted under `/api/v1/admin` alongside
//! the script CRUD endpoints; the picloud binary wires the
//! `RouteTable` shared with the orchestrator dispatcher in here so
//! writes invalidate the in-memory snapshot.

use std::sync::Arc;

use axum::{
    extract::{Path, State},
    http::StatusCode,
    response::{IntoResponse, Response},
    routing::{delete, get, post},
    Extension, Json, Router,
};
use picloud_orchestrator_core::routing::{conflict, matcher::CompiledRoute, pattern, RouteTable};
use picloud_shared::{AppId, HostKind, PathKind, Principal, Route, ScriptId};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::app_domain_repo::AppDomainRepository;
use crate::authz::{require, AuthzDenied, AuthzRepo, Capability};
use crate::repo::{ScriptRepository, ScriptRepositoryError};
use crate::route_repo::{NewRoute, RouteRepository};

pub struct RouteAdminState<RR, SR> {
    pub routes: Arc<RR>,
    /// Used to resolve `script_id → app_id` when creating routes (the
    /// route inherits the script's app) and to scope conflict checks.
    pub scripts: Arc<SR>,
    /// Used to validate the route's host against the parent app's
    /// declared domain claims.
    pub domains: Arc<dyn AppDomainRepository>,
    pub table: Arc<RouteTable>,
    /// Capability gate — Phase 3.5.
    pub authz: Arc<dyn AuthzRepo>,
}

impl<RR, SR> Clone for RouteAdminState<RR, SR> {
    fn clone(&self) -> Self {
        Self {
            routes: self.routes.clone(),
            scripts: self.scripts.clone(),
            domains: self.domains.clone(),
            table: self.table.clone(),
            authz: self.authz.clone(),
        }
    }
}

pub fn route_admin_router<RR, SR>(state: RouteAdminState<RR, SR>) -> Router
where
    RR: RouteRepository + 'static,
    SR: ScriptRepository + 'static,
{
    Router::new()
        .route(
            "/scripts/{id}/routes",
            get(list_routes::<RR, SR>).post(create_route::<RR, SR>),
        )
        .route("/routes/{route_id}", delete(delete_route::<RR, SR>))
        .route("/routes:check", post(check_route::<RR, SR>))
        .route("/routes:match", post(match_route::<RR, SR>))
        .with_state(state)
}

// ----------------------------------------------------------------------------
// DTOs
// ----------------------------------------------------------------------------

#[derive(Debug, Deserialize)]
pub struct CreateRouteRequest {
    pub host_kind: HostKind,
    #[serde(default)]
    pub host: String,
    #[serde(default)]
    pub host_param_name: Option<String>,
    pub path_kind: PathKind,
    pub path: String,
    pub method: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct CheckRouteRequest {
    /// Required: which app's route table this hypothetical route would
    /// join. Conflict checks are strictly intra-app (cross-app route
    /// errors would leak tenant info — see blueprint §11.5).
    pub app_id: AppId,
    pub host_kind: HostKind,
    #[serde(default)]
    pub host: String,
    pub path_kind: PathKind,
    pub path: String,
    pub method: Option<String>,
}

#[derive(Debug, Serialize)]
pub struct CheckRouteResponse {
    pub ok: bool,
    pub conflicting_route: Option<Route>,
    pub conflict_reason: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct MatchRouteRequest {
    /// Which app's route table to dispatch against. The dashboard's
    /// route-preview tester always knows the current app context.
    pub app_id: AppId,
    pub url: String,
    #[serde(default = "default_method")]
    pub method: String,
}

fn default_method() -> String {
    "GET".into()
}

#[derive(Debug, Serialize)]
pub struct MatchRouteResponse {
    pub matched: Option<MatchedRoute>,
}

#[derive(Debug, Serialize)]
pub struct MatchedRoute {
    pub route_id: Uuid,
    pub script_id: ScriptId,
    pub params: std::collections::BTreeMap<String, String>,
    pub rest: Option<String>,
    pub host_param: Option<(String, String)>,
}

// ----------------------------------------------------------------------------
// Handlers
// ----------------------------------------------------------------------------

async fn list_routes<RR: RouteRepository, SR: ScriptRepository>(
    State(state): State<RouteAdminState<RR, SR>>,
    Extension(principal): Extension<Principal>,
    Path(script_id): Path<ScriptId>,
) -> Result<Json<Vec<Route>>, RouteApiError> {
    let script = state
        .scripts
        .get(script_id)
        .await?
        .ok_or(RouteApiError::ScriptNotFound(script_id))?;
    require(
        state.authz.as_ref(),
        &principal,
        Capability::AppRead(script.app_id),
    )
    .await?;
    Ok(Json(state.routes.list_for_script(script_id).await?))
}

async fn create_route<RR: RouteRepository, SR: ScriptRepository>(
    State(state): State<RouteAdminState<RR, SR>>,
    Extension(principal): Extension<Principal>,
    Path(script_id): Path<ScriptId>,
    Json(input): Json<CreateRouteRequest>,
) -> Result<(StatusCode, Json<Route>), RouteApiError> {
    let normalized_path = parse_and_normalize_path(input.path_kind, &input.path)?;
    pattern::parse_host(
        input.host_kind,
        &input.host,
        input.host_param_name.as_deref(),
    )?;

    // Look up the script's owning app — every route inherits it.
    let script = state
        .scripts
        .get(script_id)
        .await?
        .ok_or(RouteApiError::ScriptNotFound(script_id))?;
    let app_id = script.app_id;
    require(
        state.authz.as_ref(),
        &principal,
        Capability::AppWriteRoute(app_id),
    )
    .await?;

    // Validate the route's host is consistent with one of the app's
    // domain claims. `HostKind::Any` is always permitted (catches every
    // host the app already owns). Specific hosts must match a claim.
    validate_route_host_against_app(state.domains.as_ref(), app_id, input.host_kind, &input.host)
        .await?;

    // Within-app conflict check (cross-app is impossible by construction).
    let existing = state.routes.list_for_app(app_id).await?;
    if let Some((conflicting, reason)) = first_conflict(
        &existing,
        input.host_kind,
        &input.host,
        input.path_kind,
        &normalized_path,
        input.method.as_deref(),
    )? {
        return Err(RouteApiError::Conflict {
            conflicting_route: Box::new(conflicting),
            reason,
        });
    }

    let created = state
        .routes
        .create(NewRoute {
            app_id,
            script_id,
            host_kind: input.host_kind,
            host: input.host,
            host_param_name: input.host_param_name,
            path_kind: input.path_kind,
            path: normalized_path,
            method: input.method,
        })
        .await?;
    refresh_table(&state).await?;
    Ok((StatusCode::CREATED, Json(created)))
}

async fn delete_route<RR: RouteRepository, SR: ScriptRepository>(
    State(state): State<RouteAdminState<RR, SR>>,
    Extension(principal): Extension<Principal>,
    Path(route_id): Path<Uuid>,
) -> Result<StatusCode, RouteApiError> {
    // Resolve the route's app before we delete, so the capability
    // binds to the actual route's app_id (not a path param).
    let route = state
        .routes
        .get(route_id)
        .await?
        .ok_or(RouteApiError::RouteNotFound(route_id))?;
    require(
        state.authz.as_ref(),
        &principal,
        Capability::AppWriteRoute(route.app_id),
    )
    .await?;
    state.routes.delete(route_id).await?;
    refresh_table(&state).await?;
    Ok(StatusCode::NO_CONTENT)
}

async fn check_route<RR: RouteRepository, SR: ScriptRepository>(
    State(state): State<RouteAdminState<RR, SR>>,
    Extension(principal): Extension<Principal>,
    Json(input): Json<CheckRouteRequest>,
) -> Result<Json<CheckRouteResponse>, RouteApiError> {
    // routes:check is read-only — peeking at a hypothetical conflict
    // is bounded by AppRead on the target app (otherwise members
    // could probe other apps).
    require(
        state.authz.as_ref(),
        &principal,
        Capability::AppRead(input.app_id),
    )
    .await?;
    let normalized_path = parse_and_normalize_path(input.path_kind, &input.path)?;
    pattern::parse_host(input.host_kind, &input.host, None)?;

    let existing = state.routes.list_for_app(input.app_id).await?;
    let conflict = first_conflict(
        &existing,
        input.host_kind,
        &input.host,
        input.path_kind,
        &normalized_path,
        input.method.as_deref(),
    )?;
    Ok(Json(match conflict {
        None => CheckRouteResponse {
            ok: true,
            conflicting_route: None,
            conflict_reason: None,
        },
        Some((route, reason)) => CheckRouteResponse {
            ok: false,
            conflicting_route: Some(route),
            conflict_reason: Some(reason),
        },
    }))
}

async fn match_route<RR: RouteRepository, SR: ScriptRepository>(
    State(state): State<RouteAdminState<RR, SR>>,
    Extension(principal): Extension<Principal>,
    Json(input): Json<MatchRouteRequest>,
) -> Result<Json<MatchRouteResponse>, RouteApiError> {
    require(
        state.authz.as_ref(),
        &principal,
        Capability::AppRead(input.app_id),
    )
    .await?;
    let parsed = url::Url::parse(&input.url)
        .map_err(|e| RouteApiError::BadRequest(format!("invalid url: {e}")))?;
    let host = parsed.host_str().unwrap_or("").to_string();
    let path = parsed.path().to_string();

    let result = state
        .table
        .match_request_for_app(input.app_id, &host, &input.method, &path);
    Ok(Json(MatchRouteResponse {
        matched: result.map(|r| MatchedRoute {
            route_id: r.matched.route_id,
            script_id: r.matched.script_id,
            params: r.params,
            rest: r.rest,
            host_param: r.host_param,
        }),
    }))
}

// ----------------------------------------------------------------------------
// Helpers
// ----------------------------------------------------------------------------

/// Validate the raw user-typed path string and return it verbatim if
/// it parses cleanly. Prefix normalization (`/echo/*` → `/echo/`)
/// happens only in memory at compile time; persisted strings stay in
/// the form the user submitted so re-parses are idempotent.
fn parse_and_normalize_path(kind: PathKind, raw: &str) -> Result<String, pattern::ParseError> {
    pattern::parse_path(kind, raw)?;
    Ok(raw.to_string())
}

#[allow(clippy::type_complexity)]
fn first_conflict(
    existing: &[Route],
    host_kind: HostKind,
    host: &str,
    path_kind: PathKind,
    path: &str,
    method: Option<&str>,
) -> Result<Option<(Route, String)>, RouteApiError> {
    let new_host = pattern::parse_host(host_kind, host, None)?;
    let new_path = pattern::parse_path(path_kind, path)?;

    for r in existing {
        let r_host = pattern::parse_host(r.host_kind, &r.host, r.host_param_name.as_deref())?;
        if !conflict::hosts_overlap(&new_host, &r_host) {
            continue;
        }
        if !conflict::methods_overlap(method, r.method.as_deref()) {
            continue;
        }
        let r_path = pattern::parse_path(r.path_kind, &r.path)?;
        if let Some(reason) = conflict::conflicts(&new_path, &r_path) {
            return Ok(Some((r.clone(), format!("{reason:?}"))));
        }
    }
    Ok(None)
}

async fn refresh_table<RR: RouteRepository, SR: ScriptRepository>(
    state: &RouteAdminState<RR, SR>,
) -> Result<(), RouteApiError> {
    let rows = state.routes.list_all().await?;
    let compiled = compile_routes(&rows)?;
    state.table.replace_all(compiled);
    Ok(())
}

pub fn compile_routes(rows: &[Route]) -> Result<Vec<CompiledRoute>, pattern::ParseError> {
    rows.iter()
        .map(|r| {
            Ok(CompiledRoute {
                route_id: r.id,
                app_id: r.app_id,
                script_id: r.script_id,
                host: pattern::parse_host(r.host_kind, &r.host, r.host_param_name.as_deref())?,
                path: pattern::parse_path(r.path_kind, &r.path)?,
                method: r.method.clone(),
            })
        })
        .collect()
}

/// Validate that a new route's (host_kind, host) is consistent with at
/// least one of the parent app's domain claims. `HostKind::Any` is
/// always permitted — it catches every host the app already owns.
async fn validate_route_host_against_app(
    domains: &dyn AppDomainRepository,
    app_id: AppId,
    host_kind: HostKind,
    host: &str,
) -> Result<(), RouteApiError> {
    if matches!(host_kind, HostKind::Any) {
        return Ok(());
    }
    let claims = domains.list_for_app(app_id).await?;
    if claims.is_empty() {
        return Err(RouteApiError::HostNotClaimed {
            host: host.to_string(),
            available_claims: vec![],
        });
    }

    let host_lower = host.to_ascii_lowercase();
    for claim in &claims {
        let claim_lower = claim.pattern.to_ascii_lowercase();
        match (host_kind, claim.shape) {
            // Strict route under exact claim: must match exactly.
            (HostKind::Strict, picloud_shared::DomainShape::Exact) => {
                if host_lower == claim_lower {
                    return Ok(());
                }
            }
            // Strict route under wildcard/parameterized: must end with
            // ".<suffix>" where the claim's suffix is the part after
            // `*.` or `{...}.`.
            (
                HostKind::Strict,
                picloud_shared::DomainShape::Wildcard | picloud_shared::DomainShape::Parameterized,
            ) => {
                let suffix = claim_lower
                    .split_once('.')
                    .map(|(_, s)| s.to_string())
                    .unwrap_or_default();
                let needle = format!(".{suffix}");
                if !suffix.is_empty() && host_lower.ends_with(&needle) {
                    return Ok(());
                }
            }
            // Wildcard route: must match a wildcard or parameterized
            // claim with identical suffix.
            (
                HostKind::Wildcard,
                picloud_shared::DomainShape::Wildcard | picloud_shared::DomainShape::Parameterized,
            ) => {
                let claim_suffix = claim_lower
                    .split_once('.')
                    .map(|(_, s)| s.to_string())
                    .unwrap_or_default();
                if claim_suffix == host_lower {
                    return Ok(());
                }
            }
            // Wildcard route under exact claim: not allowed (would
            // shadow other apps' subdomains the operator didn't claim).
            (HostKind::Wildcard, picloud_shared::DomainShape::Exact) => {}
            (HostKind::Any, _) => unreachable!("handled above"),
        }
    }

    Err(RouteApiError::HostNotClaimed {
        host: host.to_string(),
        available_claims: claims.into_iter().map(|c| c.pattern).collect(),
    })
}

// ----------------------------------------------------------------------------
// Errors
// ----------------------------------------------------------------------------

#[derive(Debug, thiserror::Error)]
pub enum RouteApiError {
    #[error("route conflicts with existing route ({reason})")]
    Conflict {
        conflicting_route: Box<Route>,
        reason: String,
    },

    #[error("invalid route: {0}")]
    Pattern(#[from] pattern::ParseError),

    #[error("bad request: {0}")]
    BadRequest(String),

    #[error("script not found: {0}")]
    ScriptNotFound(ScriptId),

    #[error("route not found: {0}")]
    RouteNotFound(Uuid),

    #[error("host {host:?} is not claimed by this app")]
    HostNotClaimed {
        host: String,
        available_claims: Vec<String>,
    },

    #[error("forbidden")]
    Forbidden,

    #[error("authorization repo error: {0}")]
    AuthzRepo(String),

    #[error("repository error: {0}")]
    Repo(#[from] ScriptRepositoryError),
}

impl From<AuthzDenied> for RouteApiError {
    fn from(d: AuthzDenied) -> Self {
        match d {
            AuthzDenied::Denied => Self::Forbidden,
            AuthzDenied::Repo(e) => Self::AuthzRepo(e.to_string()),
        }
    }
}

impl IntoResponse for RouteApiError {
    fn into_response(self) -> Response {
        let (status, body) = match &self {
            Self::Conflict {
                conflicting_route,
                reason,
            } => (
                StatusCode::CONFLICT,
                serde_json::json!({
                    "error": self.to_string(),
                    "reason": reason,
                    "conflicting_route": &**conflicting_route,
                }),
            ),
            Self::Pattern(_) | Self::BadRequest(_) => (
                StatusCode::UNPROCESSABLE_ENTITY,
                serde_json::json!({ "error": self.to_string() }),
            ),
            Self::ScriptNotFound(_)
            | Self::RouteNotFound(_)
            | Self::Repo(ScriptRepositoryError::NotFound(_)) => (
                StatusCode::NOT_FOUND,
                serde_json::json!({ "error": self.to_string() }),
            ),
            Self::Forbidden => (
                StatusCode::FORBIDDEN,
                serde_json::json!({ "error": self.to_string() }),
            ),
            Self::AuthzRepo(e) => {
                tracing::error!(error = %e, "route authz repo error");
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    serde_json::json!({ "error": "internal error" }),
                )
            }
            Self::HostNotClaimed {
                host,
                available_claims,
            } => (
                StatusCode::UNPROCESSABLE_ENTITY,
                serde_json::json!({
                    "error": self.to_string(),
                    "host": host,
                    "available_claims": available_claims,
                }),
            ),
            Self::Repo(ScriptRepositoryError::Conflict(_)) => (
                StatusCode::CONFLICT,
                serde_json::json!({ "error": self.to_string() }),
            ),
            Self::Repo(ScriptRepositoryError::Db(e)) => {
                tracing::error!(error = %e, "route admin db error");
                (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    serde_json::json!({ "error": "internal error" }),
                )
            }
        };
        (status, Json(body)).into_response()
    }
}