use axum::{
    Json, Router,
    body::Body,
    extract::{Path, Query, State},
    http::{Extensions, StatusCode},
    response::{IntoResponse, Response},
    routing::{get, post},
};
use fc_common::{
    Build, BuildProduct, BuildStatus, BuildStep, CreateBuild, PaginatedResponse, PaginationParams,
};
use serde::Deserialize;
use uuid::Uuid;

use crate::auth_middleware::RequireRoles;
use crate::error::ApiError;
use crate::state::AppState;

fn check_role(extensions: &Extensions, allowed: &[&str]) -> Result<(), ApiError> {
    RequireRoles::check(extensions, allowed)
        .map(|_| ())
        .map_err(|s| {
            ApiError(if s == StatusCode::FORBIDDEN {
                fc_common::CiError::Forbidden("Insufficient permissions".to_string())
            } else {
                fc_common::CiError::Unauthorized("Authentication required".to_string())
            })
        })
}

#[derive(Debug, Deserialize)]
struct ListBuildsParams {
    evaluation_id: Option<Uuid>,
    status: Option<String>,
    system: Option<String>,
    job_name: Option<String>,
    limit: Option<i64>,
    offset: Option<i64>,
}

async fn list_builds(
    State(state): State<AppState>,
    Query(params): Query<ListBuildsParams>,
) -> Result<Json<PaginatedResponse<Build>>, ApiError> {
    let pagination = PaginationParams {
        limit: params.limit,
        offset: params.offset,
    };
    let limit = pagination.limit();
    let offset = pagination.offset();
    let items = fc_common::repo::builds::list_filtered(
        &state.pool,
        params.evaluation_id,
        params.status.as_deref(),
        params.system.as_deref(),
        params.job_name.as_deref(),
        limit,
        offset,
    )
    .await
    .map_err(ApiError)?;
    let total = fc_common::repo::builds::count_filtered(
        &state.pool,
        params.evaluation_id,
        params.status.as_deref(),
        params.system.as_deref(),
        params.job_name.as_deref(),
    )
    .await
    .map_err(ApiError)?;
    Ok(Json(PaginatedResponse {
        items,
        total,
        limit,
        offset,
    }))
}

async fn get_build(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Build>, ApiError> {
    let build = fc_common::repo::builds::get(&state.pool, id)
        .await
        .map_err(ApiError)?;
    Ok(Json(build))
}

async fn cancel_build(
    extensions: Extensions,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Vec<Build>>, ApiError> {
    check_role(&extensions, &["cancel-build"])?;
    let cancelled = fc_common::repo::builds::cancel_cascade(&state.pool, id)
        .await
        .map_err(ApiError)?;
    if cancelled.is_empty() {
        return Err(ApiError(fc_common::CiError::NotFound(
            "Build not found or not in a cancellable state".to_string(),
        )));
    }
    Ok(Json(cancelled))
}

async fn list_build_steps(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Vec<BuildStep>>, ApiError> {
    let steps = fc_common::repo::build_steps::list_for_build(&state.pool, id)
        .await
        .map_err(ApiError)?;
    Ok(Json(steps))
}

async fn list_build_products(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Vec<BuildProduct>>, ApiError> {
    let products = fc_common::repo::build_products::list_for_build(&state.pool, id)
        .await
        .map_err(ApiError)?;
    Ok(Json(products))
}

async fn build_stats(
    State(state): State<AppState>,
) -> Result<Json<fc_common::BuildStats>, ApiError> {
    let stats = fc_common::repo::builds::get_stats(&state.pool)
        .await
        .map_err(ApiError)?;
    Ok(Json(stats))
}

async fn recent_builds(State(state): State<AppState>) -> Result<Json<Vec<Build>>, ApiError> {
    let builds = fc_common::repo::builds::list_recent(&state.pool, 20)
        .await
        .map_err(ApiError)?;
    Ok(Json(builds))
}

async fn list_project_builds(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Vec<Build>>, ApiError> {
    let builds = fc_common::repo::builds::list_for_project(&state.pool, id)
        .await
        .map_err(ApiError)?;
    Ok(Json(builds))
}

async fn restart_build(
    extensions: Extensions,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Build>, ApiError> {
    check_role(&extensions, &["restart-jobs"])?;
    let original = fc_common::repo::builds::get(&state.pool, id)
        .await
        .map_err(ApiError)?;

    // Can only restart completed or failed builds
    if original.status != BuildStatus::Failed
        && original.status != BuildStatus::Completed
        && original.status != BuildStatus::Cancelled
    {
        return Err(ApiError(fc_common::CiError::Validation(
            "Can only restart failed, completed, or cancelled builds".to_string(),
        )));
    }

    // Create a new build with the same parameters
    let new_build = fc_common::repo::builds::create(
        &state.pool,
        CreateBuild {
            evaluation_id: original.evaluation_id,
            job_name: original.job_name.clone(),
            drv_path: original.drv_path.clone(),
            system: original.system.clone(),
            outputs: original.outputs.clone(),
            is_aggregate: Some(original.is_aggregate),
            constituents: original.constituents.clone(),
        },
    )
    .await
    .map_err(ApiError)?;

    tracing::info!(
        original_id = %id,
        new_id = %new_build.id,
        job = %original.job_name,
        "Build restarted"
    );

    Ok(Json(new_build))
}

async fn bump_build(
    extensions: Extensions,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<Json<Build>, ApiError> {
    check_role(&extensions, &["bump-to-front"])?;
    let build = sqlx::query_as::<_, Build>(
        "UPDATE builds SET priority = priority + 10 WHERE id = $1 AND status = 'pending' RETURNING *",
    )
    .bind(id)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| ApiError(fc_common::CiError::Database(e)))?
    .ok_or_else(|| {
        ApiError(fc_common::CiError::Validation(
            "Build not found or not in pending state".to_string(),
        ))
    })?;

    Ok(Json(build))
}

async fn download_build_product(
    State(state): State<AppState>,
    Path((build_id, product_id)): Path<(Uuid, Uuid)>,
) -> Result<Response, ApiError> {
    // Verify build exists
    let _build = fc_common::repo::builds::get(&state.pool, build_id)
        .await
        .map_err(ApiError)?;

    let product = fc_common::repo::build_products::get(&state.pool, product_id)
        .await
        .map_err(ApiError)?;

    if product.build_id != build_id {
        return Err(ApiError(fc_common::CiError::NotFound(
            "Product does not belong to this build".to_string(),
        )));
    }

    if !fc_common::validate::is_valid_store_path(&product.path) {
        return Err(ApiError(fc_common::CiError::Validation(
            "Invalid store path".to_string(),
        )));
    }

    if product.is_directory {
        // Stream as NAR using nix store dump-path
        let child = tokio::process::Command::new("nix")
            .args(["store", "dump-path", &product.path])
            .stdout(std::process::Stdio::piped())
            .stderr(std::process::Stdio::null())
            .spawn();

        let mut child = match child {
            Ok(c) => c,
            Err(e) => {
                return Err(ApiError(fc_common::CiError::Build(format!(
                    "Failed to dump path: {e}"
                ))));
            }
        };

        let stdout = match child.stdout.take() {
            Some(s) => s,
            None => {
                return Err(ApiError(fc_common::CiError::Build(
                    "Failed to capture output".to_string(),
                )));
            }
        };

        let stream = tokio_util::io::ReaderStream::new(stdout);
        let body = Body::from_stream(stream);

        let filename = product.path.rsplit('/').next().unwrap_or(&product.name);

        Ok((
            StatusCode::OK,
            [
                ("content-type", "application/x-nix-nar"),
                (
                    "content-disposition",
                    &format!("attachment; filename=\"{filename}.nar\""),
                ),
            ],
            body,
        )
            .into_response())
    } else {
        // Serve file directly
        let file = tokio::fs::File::open(&product.path)
            .await
            .map_err(|e| ApiError(fc_common::CiError::Io(e)))?;

        let stream = tokio_util::io::ReaderStream::new(file);
        let body = Body::from_stream(stream);

        let content_type = product
            .content_type
            .as_deref()
            .unwrap_or("application/octet-stream");
        let filename = product.path.rsplit('/').next().unwrap_or(&product.name);

        Ok((
            StatusCode::OK,
            [
                ("content-type", content_type),
                (
                    "content-disposition",
                    &format!("attachment; filename=\"{filename}\""),
                ),
            ],
            body,
        )
            .into_response())
    }
}

pub fn router() -> Router<AppState> {
    Router::new()
        .route("/builds", get(list_builds))
        .route("/builds/stats", get(build_stats))
        .route("/builds/recent", get(recent_builds))
        .route("/builds/{id}", get(get_build))
        .route("/builds/{id}/cancel", post(cancel_build))
        .route("/builds/{id}/restart", post(restart_build))
        .route("/builds/{id}/bump", post(bump_build))
        .route("/builds/{id}/steps", get(list_build_steps))
        .route("/builds/{id}/products", get(list_build_products))
        .route(
            "/builds/{build_id}/products/{product_id}/download",
            get(download_build_product),
        )
        .route("/projects/{id}/builds", get(list_project_builds))
}