//! Syntheses CRUD handlers.
//!
//! - `GET /api/v1/syntheses` — list user's syntheses (paginated)
//! - `GET /api/v1/syntheses/:id` — get synthesis detail
//! - `DELETE /api/v1/syntheses/:id` — delete a synthesis
//! - `POST /api/v1/syntheses/:id/send-email` — send synthesis by email
//! - `GET /api/v1/syntheses/:id/export/markdown` — export as Markdown
//! - `GET /api/v1/syntheses/:id/export/pdf` — export as PDF

use axum::extract::{Path, Query, State};
use axum::http::{header, StatusCode};
use axum::response::IntoResponse;
use axum::Json;
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::app_state::AppState;
use crate::db;
use crate::errors::AppError;
use crate::middleware::auth::AuthUser;
use crate::models::synthesis::{
    NewsSection, SendEmailRequest, SynthesisListItem, SynthesisResponse,
};
use crate::services::email;
use crate::services::export;

/// Query parameters for `GET /api/v1/syntheses`.
#[derive(Debug, Deserialize)]
pub struct ListQuery {
    /// Maximum number of syntheses to return (default: 20, max: 100).
    pub limit: Option<i64>,
    /// Number of syntheses to skip (default: 0).
    pub offset: Option<i64>,
}

/// Response for `GET /api/v1/syntheses`.
#[derive(Debug, Serialize)]
pub struct ListResponse {
    pub items: Vec<SynthesisListItem>,
}

/// `GET /api/v1/syntheses`
///
/// Returns a paginated list of the authenticated user's syntheses,
/// ordered by creation date (newest first). Each item includes a
/// preview of the first section.
pub async fn list(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Query(params): Query<ListQuery>,
) -> Result<impl IntoResponse, AppError> {
    let limit = params.limit.unwrap_or(20).clamp(1, 100);
    let offset = params.offset.unwrap_or(0).max(0);

    let rows =
        db::syntheses::list_for_user(&state.pool, auth_user.id, limit, offset).await?;

    let items: Vec<SynthesisListItem> = rows
        .into_iter()
        .map(|row| {
            let theme_name = row.theme_name.clone();
            let synthesis = crate::models::synthesis::Synthesis {
                id: row.id,
                user_id: row.user_id,
                week: row.week,
                sections: row.sections,
                status: row.status,
                created_at: row.created_at,
                job_id: row.job_id,
                theme_id: row.theme_id,
            };
            let mut item = SynthesisListItem::try_from(synthesis)?;
            item.theme_name = theme_name;
            Ok(item)
        })
        .collect::<Result<Vec<_>, AppError>>()?;

    Ok(Json(ListResponse { items }))
}

/// `GET /api/v1/syntheses/:id`
///
/// Returns the full synthesis detail including all sections and items.
/// Enforces ownership: a user can only view their own syntheses.
pub async fn get(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, AppError> {
    let synthesis = db::syntheses::get_by_id_for_user(&state.pool, id, auth_user.id)
        .await?
        .ok_or_else(|| AppError::NotFound("Synthese introuvable.".into()))?;

    let response = SynthesisResponse::try_from(synthesis)?;

    Ok(Json(response))
}

/// `DELETE /api/v1/syntheses/:id`
///
/// Deletes a synthesis by ID. Enforces ownership: a user can only
/// delete their own syntheses. Returns 204 No Content on success.
pub async fn delete(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, AppError> {
    let deleted = db::syntheses::delete(&state.pool, id, auth_user.id).await?;

    if !deleted {
        return Err(AppError::NotFound("Synthese introuvable.".into()));
    }

    tracing::info!(
        user_id = %auth_user.id,
        synthesis_id = %id,
        "Synthesis deleted"
    );

    Ok(StatusCode::NO_CONTENT)
}

/// Helper: fetch a synthesis for the authenticated user and parse its sections.
async fn fetch_owned_synthesis(
    state: &AppState,
    user_id: uuid::Uuid,
    synthesis_id: uuid::Uuid,
) -> Result<(String, String, Vec<NewsSection>), AppError> {
    let synthesis = db::syntheses::get_by_id_for_user(&state.pool, synthesis_id, user_id)
        .await?
        .ok_or_else(|| AppError::NotFound("Synthese introuvable.".into()))?;

    let sections: Vec<NewsSection> =
        serde_json::from_value(synthesis.sections).map_err(|e| {
            AppError::Internal(anyhow::anyhow!(
                "Failed to parse synthesis sections: {}",
                e
            ))
        })?;

    let date = synthesis.created_at.format("%Y-%m-%d").to_string();

    Ok((synthesis.week, date, sections))
}

/// Response for `POST /api/v1/syntheses/:id/send-email`.
#[derive(Debug, Serialize)]
pub struct SendEmailResponse {
    pub message: String,
}

/// `POST /api/v1/syntheses/:id/send-email`
///
/// Sends the synthesis to the specified email address via Resend.
/// Validates the email address and enforces ownership.
pub async fn send_email(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
    Json(body): Json<SendEmailRequest>,
) -> Result<impl IntoResponse, AppError> {
    body.validate()?;

    let (week, date, sections) = fetch_owned_synthesis(&state, auth_user.id, id).await?;

    email::send_synthesis_email(
        &state.http_client,
        &state.config.resend_api_key,
        &state.config.email_from,
        &body.email,
        &week,
        &date,
        &sections,
    )
    .await?;

    tracing::info!(
        user_id = %auth_user.id,
        synthesis_id = %id,
        to = %body.email,
        "Synthesis sent by email"
    );

    Ok(Json(SendEmailResponse {
        message: "Email envoye avec succes.".into(),
    }))
}

/// `GET /api/v1/syntheses/:id/export/markdown`
///
/// Returns the synthesis as a downloadable Markdown file.
/// Content-Type: text/markdown, with Content-Disposition for download.
pub async fn export_markdown(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, AppError> {
    let (week, date, sections) = fetch_owned_synthesis(&state, auth_user.id, id).await?;

    let markdown = export::generate_markdown(&week, &date, &sections);
    let filename = format!("synthese-{}.md", week);

    Ok((
        StatusCode::OK,
        [
            (header::CONTENT_TYPE, "text/markdown; charset=utf-8".to_string()),
            (
                header::CONTENT_DISPOSITION,
                format!("attachment; filename=\"{}\"", filename),
            ),
        ],
        markdown,
    ))
}

/// `GET /api/v1/syntheses/:id/export/pdf`
///
/// Returns the synthesis as a downloadable PDF file.
/// Content-Type: application/pdf, with Content-Disposition for download.
pub async fn export_pdf(
    auth_user: AuthUser,
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, AppError> {
    let (week, date, sections) = fetch_owned_synthesis(&state, auth_user.id, id).await?;

    let pdf_bytes = export::generate_pdf(&week, &date, &sections)?;
    let filename = format!("synthese-{}.pdf", week);

    Ok((
        StatusCode::OK,
        [
            (header::CONTENT_TYPE, "application/pdf".to_string()),
            (
                header::CONTENT_DISPOSITION,
                format!("attachment; filename=\"{}\"", filename),
            ),
        ],
        pdf_bytes,
    ))
}