//! The request handlers behind the six table-definition pages.
//!
//! Each page has a GET that renders it and, except for the read-only history,
//! a POST per write it offers. A write answers with its own page's body,
//! re-read from the backend, so what the user sees after a change is the
//! definition as it now is rather than the form they submitted. A refused
//! write answers the same way but with 422 and the backend's own message,
//! which `ui/base.html` swaps in because a 4xx still carries the explanation.
//!
//! Two exceptions. Staging a column changes nothing on the server, so those
//! interactions swap only the column panel. And a successful delete leaves no
//! page to return to — the table it was about is gone — so it redirects to the
//! admin panel instead.

use axum::{
    extract::{Query, State},
    http::{HeaderMap, HeaderValue, StatusCode},
    response::{Html, IntoResponse, Redirect, Response},
};
use axum_extra::extract::Form;

use crate::{
    AppState,
    definitions::table_definition::{
        AddTableColumnsRequest, CopyProfileRequest, CreateInvoiceTemplateTableRequest,
        ColumnPresentation, DeleteTableRequest, SetColumnPresentationRequest,
    },
    {i18n::Locale, tr},
    schema::{ColumnForm, proto_columns},
    services::{authenticated_request, reject_cross_site},
};

use super::{
    loader::{self, load_page},
    state::{
        AliasForm, CopyForm, DeleteForm, DetailColumn, GeneratedTableView, InvoiceTemplateForm,
        LoadError, OrderForm, PageInputs, Selection, TableDefinitionPageState,
    },
    ui,
};

/// Which page a response belongs to: what the switcher marks as current, and
/// which fragment a write on it swaps back.
#[derive(Clone, Copy)]
enum Page {
    AddColumns,
    Presentation,
    Delete,
    Copy,
    Template,
    History,
}

impl Page {
    fn name(self) -> &'static str {
        match self {
            Self::AddColumns => "add-columns",
            Self::Presentation => "presentation",
            Self::Delete => "delete",
            Self::Copy => "copy",
            Self::Template => "template",
            Self::History => "history",
        }
    }

    fn render_page(self, page: &TableDefinitionPageState) -> String {
        match self {
            Self::AddColumns => ui::render_add_columns_page(page),
            Self::Presentation => ui::render_presentation_page(page),
            Self::Delete => ui::render_delete_page(page),
            Self::Copy => ui::render_copy_page(page),
            Self::Template => ui::render_template_page(page),
            Self::History => ui::render_history_page(page),
        }
    }

    /// The `#table-panel` swap. History has no writes, so it never asks.
    fn render_fragment(self, page: &TableDefinitionPageState) -> String {
        match self {
            Self::AddColumns => ui::render_add_columns_fragment(page),
            Self::Presentation => ui::render_presentation_fragment(page),
            Self::Delete => ui::render_delete_fragment(page),
            Self::Copy => ui::render_copy_fragment(page),
            Self::Template => ui::render_template_fragment(page),
            Self::History => ui::render_history_page(page),
        }
    }
}

// ── The pages ───────────────────────────────────────────────────────────────

/// GET /admin/tables/columns/add
pub(crate) async fn add_columns_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, PageInputs::for_selection(selection), Page::AddColumns).await
}

/// GET /admin/tables/presentation
pub(crate) async fn presentation_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, PageInputs::for_selection(selection), Page::Presentation).await
}

/// GET /admin/tables/delete
pub(crate) async fn delete_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, PageInputs::for_selection(selection), Page::Delete).await
}

/// GET /admin/profiles/copy
pub(crate) async fn copy_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, profile_inputs(selection), Page::Copy).await
}

/// GET /admin/tables/from-template
pub(crate) async fn template_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, profile_inputs(selection), Page::Template).await
}

/// GET /admin/profiles/history
pub(crate) async fn history_page(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
) -> Response {
    show(state, headers, PageInputs::for_selection(selection), Page::History).await
}

/// The profile-wide pages act on a profile, so a table in the query is
/// dropped rather than carried into a form that has no use for it.
fn profile_inputs(selection: Selection) -> PageInputs {
    PageInputs::for_selection(Selection {
        profile: selection.profile,
        table: String::new(),
    })
}

async fn show(state: AppState, headers: HeaderMap, inputs: PageInputs, page: Page) -> Response {
    match load_page(state, &headers, inputs).await {
        Ok(mut loaded) => {
            loaded.active = page.name();
            Html(page.render_page(&loaded)).into_response()
        }
        Err(error) => load_error_response(&headers, error),
    }
}

// ── The writes ──────────────────────────────────────────────────────────────

/// POST /admin/tables/columns/add/builder — staging a column to append.
///
/// Nothing is written here; the panel is swapped back with the column added,
/// removed, or its index toggled, exactly as the Add-table builder works.
pub(crate) async fn update_columns(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
    Form(form): Form<ColumnForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    // Staging a column applies the vocabulary's rules, so it is read before
    // the panel is rebuilt; `load_page` reuses what is read here.
    let mut definitions = state.definitions.clone();
    let catalog = match loader::load_column_catalog(&mut definitions, &headers).await {
        Ok(catalog) => catalog,
        Err(error) => return load_error_response(&headers, error),
    };

    let mut inputs = PageInputs::for_selection(selection);
    inputs.columns = form.to_draft(catalog, false);

    let index = form.index.unwrap_or(0);
    let locale = Locale::from_headers(&headers);
    match form.action.as_str() {
        "add-column" => match inputs.columns.add_from_inputs(locale) {
            Ok(status) => inputs.status = Some(status),
            Err(message) => inputs.error = Some(message),
        },
        "remove-column" => {
            if let Err(message) = inputs.columns.remove(locale, index) {
                inputs.error = Some(message);
            }
        }
        "toggle-index" => inputs.columns.toggle_indexed(index),
        _ => {}
    }

    match load_page(state, &headers, inputs).await {
        Ok(mut loaded) => {
            loaded.active = Page::AddColumns.name();
            Html(ui::render_column_panel(&loaded)).into_response()
        }
        Err(error) => load_error_response(&headers, error),
    }
}

/// POST /admin/tables/columns/add — AddTableColumns.
pub(crate) async fn add_columns(
    State(state): State<AppState>,
    headers: HeaderMap,
    Query(selection): Query<Selection>,
    Form(form): Form<ColumnForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    // The draft is validated before the write, so the vocabulary it is held to
    // is read first; `load_page` reuses what is read here.
    let mut definitions = state.definitions.clone();
    let catalog = match loader::load_column_catalog(&mut definitions, &headers).await {
        Ok(catalog) => catalog,
        Err(error) => return load_error_response(&headers, error),
    };

    let mut inputs = PageInputs::for_selection(selection);
    inputs.columns = form.to_draft(catalog.clone(), false);

    if !inputs.selection.has_table() {
        let message = tr!(
            Locale::from_headers(&headers),
            "td-err-select-table-first"
        );
        return refuse(
            state,
            headers,
            inputs,
            Page::AddColumns,
            message,
        )
        .await;
    }
    if inputs.columns.is_empty() {
        let message = tr!(
            Locale::from_headers(&headers),
            "td-err-describe-column"
        );
        return refuse(
            state,
            headers,
            inputs,
            Page::AddColumns,
            message,
        )
        .await;
    }
    // The same checks the server runs, applied to a draft that may have been
    // rebuilt from a posted form rather than through the panel.
    if let Err(message) = inputs.columns.validate(Locale::from_headers(&headers)) {
        return refuse(state, headers, inputs, Page::AddColumns, message).await;
    }

    let request = AddTableColumnsRequest {
        profile_name: inputs.selection.profile.clone(),
        table_name: inputs.selection.table.clone(),
        columns: proto_columns(&inputs.columns.added),
        indexes: inputs.columns.selected_index_names(),
        // The append panel names its columns itself; the only generated ones it
        // can produce are the phone and IBAN companions, which it does not
        // offer to rename. The table's own rename form is where that is done.
        generated_aliases: Vec::new(),
    };
    let Ok(request) = authenticated_request(&headers, request) else {
        return Redirect::to("/login").into_response();
    };

    match definitions.add_table_columns(request).await {
        Ok(response) if response.get_ref().success => {
            let added = inputs.columns.added.len();
            inputs.sql = Some(response.into_inner().sql);
            inputs.status = Some(tr!(
                Locale::from_headers(&headers),
                "td-columns-added",
                "count" => added as i64,
                "table" => inputs.selection.table.clone(),
            ));
            // The columns are the table's now, so the panel starts empty.
            inputs.columns = crate::schema::ColumnDraft::for_append(catalog);
            respond(state, headers, inputs, Page::AddColumns, StatusCode::OK).await
        }
        Ok(response) => {
            let message = response.into_inner().sql;
            let message = if message.is_empty() {
                tr!(
                    Locale::from_headers(&headers),
                    "td-err-backend-no-columns"
                )
            } else {
                message
            };
            refuse(state, headers, inputs, Page::AddColumns, message).await
        }
        Err(error) => {
            refuse(state, headers, inputs, Page::AddColumns, error.message().to_string()).await
        }
    }
}

/// POST /admin/tables/presentation/alias — SetColumnPresentation, renaming one
/// column.
///
/// The request the backend wants is the whole table, so the columns this write
/// is not about are filled in from a fresh read rather than from the browser.
/// That is the point of the split: the only thing the form contributes is the
/// alias and the id of the column it was typed into.
pub(crate) async fn set_column_alias(
    State(state): State<AppState>,
    headers: HeaderMap,
    Form(form): Form<AliasForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    let inputs = PageInputs::for_selection(Selection {
        profile: form.profile.clone(),
        table: form.table.clone(),
    });

    let alias = form.alias.trim().to_string();
    if alias.is_empty() {
        let message = tr!(Locale::from_headers(&headers), "td-err-choose-rename");
        return refuse(state, headers, inputs, Page::Presentation, message).await;
    }

    let columns = match current_columns(&state, &headers, &inputs).await {
        Ok(columns) => columns,
        Err(response) => return response,
    };
    if !columns.iter().any(|column| column.column_id == form.column_id) {
        let message = tr!(Locale::from_headers(&headers), "td-err-unknown-column");
        return refuse(state, headers, inputs, Page::Presentation, message).await;
    }
    let presentation = columns
        .iter()
        .map(|column| ColumnPresentation {
            column_id: column.column_id,
            alias: if column.column_id == form.column_id {
                alias.clone()
            } else {
                column.name.clone()
            },
        })
        .collect();

    apply_presentation(
        state,
        headers,
        inputs,
        form.profile,
        form.table,
        form.expected_row_version,
        presentation,
    )
    .await
}

/// POST /admin/tables/presentation/order — SetColumnPresentation, saving the
/// order staged by the browser.
///
/// Every alias in the request is the name the backend just reported, so this
/// write cannot rename a column. The ids from the browser must be an exact
/// permutation of the current columns before their order is accepted.
pub(crate) async fn set_column_order(
    State(state): State<AppState>,
    headers: HeaderMap,
    Form(form): Form<OrderForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    let inputs = PageInputs::for_selection(Selection {
        profile: form.profile.clone(),
        table: form.table.clone(),
    });

    let columns = match current_columns(&state, &headers, &inputs).await {
        Ok(columns) => columns,
        Err(response) => return response,
    };
    let current_ids = columns
        .iter()
        .map(|column| column.column_id)
        .collect::<std::collections::HashSet<_>>();
    let submitted_ids = form
        .column_ids
        .iter()
        .copied()
        .collect::<std::collections::HashSet<_>>();
    if form.column_ids.len() != columns.len()
        || submitted_ids.len() != form.column_ids.len()
        || submitted_ids != current_ids
    {
        let message = tr!(Locale::from_headers(&headers), "td-err-invalid-order");
        return refuse(state, headers, inputs, Page::Presentation, message).await;
    }

    let columns_by_id = columns
        .iter()
        .map(|column| (column.column_id, column))
        .collect::<std::collections::HashMap<_, _>>();
    let presentation = form
        .column_ids
        .iter()
        .map(|column_id| {
            let column = columns_by_id[column_id];
            ColumnPresentation {
                column_id: *column_id,
                alias: column.name.clone(),
            }
        })
        .collect();

    apply_presentation(
        state,
        headers,
        inputs,
        form.profile,
        form.table,
        form.expected_row_version,
        presentation,
    )
    .await
}

/// The table's columns as the backend has them now, in their current order.
///
/// Both presentation writes have to send every column, and the ones they are
/// not about must carry the name the server holds this moment -- not the name
/// the browser was showing when the page was drawn.
async fn current_columns(
    state: &AppState,
    headers: &HeaderMap,
    inputs: &PageInputs,
) -> Result<Vec<DetailColumn>, Response> {
    match load_page(state.clone(), headers, inputs.clone()).await {
        Ok(page) => Ok(page.detail.map(|detail| detail.columns).unwrap_or_default()),
        Err(error) => Err(load_error_response(headers, error)),
    }
}

/// The half both writes share: send the presentation, answer with the page.
///
/// `expected_row_version` is the browser's, not the one the read above saw, so
/// a definition that changed under the user is still refused by the backend
/// rather than silently written over.
async fn apply_presentation(
    state: AppState,
    headers: HeaderMap,
    inputs: PageInputs,
    profile: String,
    table: String,
    expected_row_version: i64,
    columns: Vec<ColumnPresentation>,
) -> Response {
    let request = SetColumnPresentationRequest {
        profile_name: profile,
        table_name: table,
        columns,
        expected_row_version,
    };
    let Ok(request) = authenticated_request(&headers, request) else {
        return Redirect::to("/login").into_response();
    };

    let mut definitions = state.definitions.clone();
    match definitions.set_column_presentation(request).await {
        Ok(response) if response.get_ref().success => {
            let mut inputs = inputs;
            inputs.status = Some(response.into_inner().message);
            respond(state, headers, inputs, Page::Presentation, StatusCode::OK).await
        }
        Ok(response) => {
            let message = response.into_inner().message;
            let message = if message.is_empty() {
                tr!(Locale::from_headers(&headers), "td-err-backend-no-rename")
            } else {
                message
            };
            refuse(state, headers, inputs, Page::Presentation, message).await
        }
        Err(error) => {
            refuse(
                state,
                headers,
                inputs,
                Page::Presentation,
                error.message().to_string(),
            )
            .await
        }
    }
}

/// POST /admin/tables/delete — DeleteTable.
///
/// On success there is nothing left for this page to show, so it hands the
/// browser to the admin panel with the profile still selected.
pub(crate) async fn delete_table(
    State(state): State<AppState>,
    headers: HeaderMap,
    Form(form): Form<DeleteForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    let inputs = PageInputs::for_selection(Selection {
        profile: form.profile.clone(),
        table: form.table.clone(),
    });

    // The typed name is the whole guard: the drop is CASCADE, and it takes the
    // profile with it when this was its last table.
    if form.confirm_table_name.trim() != form.table || form.table.is_empty() {
        let message = tr!(
            Locale::from_headers(&headers),
            "td-err-type-name"
        );
        return refuse(
            state,
            headers,
            inputs,
            Page::Delete,
            message,
        )
        .await;
    }

    let request = DeleteTableRequest {
        profile_name: form.profile.clone(),
        table_name: form.table.clone(),
    };
    let Ok(request) = authenticated_request(&headers, request) else {
        return Redirect::to("/login").into_response();
    };

    let mut definitions = state.definitions.clone();
    match definitions.delete_table(request).await {
        Ok(response) if response.get_ref().success => {
            // The profile may have gone with it, in which case the admin panel
            // refuses the selection; landing on the bare panel is what the
            // caller wants then anyway.
            let location = format!("/admin?profile={}", form.profile);
            match HeaderValue::try_from(location) {
                Ok(location) => {
                    let mut response = Html(String::new()).into_response();
                    response.headers_mut().insert("hx-redirect", location);
                    response
                }
                Err(_) => (
                    StatusCode::INTERNAL_SERVER_ERROR,
                    Html(tr!(
                        Locale::from_headers(&headers),
                        "ui-err-invalid-redirect"
                    )),
                )
                    .into_response(),
            }
        }
        Ok(response) => {
            let message = response.into_inner().message;
            let message = if message.is_empty() {
                tr!(
                    Locale::from_headers(&headers),
                    "td-err-backend-no-delete"
                )
            } else {
                message
            };
            refuse(state, headers, inputs, Page::Delete, message).await
        }
        Err(error) => {
            refuse(state, headers, inputs, Page::Delete, error.message().to_string()).await
        }
    }
}

/// POST /admin/profiles/copy — CopyProfile.
pub(crate) async fn copy_profile(
    State(state): State<AppState>,
    headers: HeaderMap,
    Form(form): Form<CopyForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    let mut inputs = PageInputs::for_selection(Selection {
        profile: form.profile.clone(),
        table: String::new(),
    });
    inputs.copy = form.clone();

    if form.target_profile_name.trim().is_empty() {
        let message = tr!(
            Locale::from_headers(&headers),
            "td-err-name-profile"
        );
        return refuse(
            state,
            headers,
            inputs,
            Page::Copy,
            message,
        )
        .await;
    }

    let request = CopyProfileRequest {
        source_profile_name: form.profile.clone(),
        target_profile_name: form.target_profile_name.trim().to_string(),
        // No table selected means the whole profile, which is what the hint
        // promises and what the server does with an empty list. A browser
        // sends no `table_names` key at all when nothing is ticked; anything
        // posting the field empty would otherwise send one blank name, and
        // the server rejects a blank name rather than reading it as "all".
        table_names: form
            .table_names
            .iter()
            .map(|name| name.trim())
            .filter(|name| !name.is_empty())
            .map(str::to_string)
            .collect(),
    };
    let Ok(request) = authenticated_request(&headers, request) else {
        return Redirect::to("/login").into_response();
    };

    let mut definitions = state.definitions.clone();
    match definitions.copy_profile(request).await {
        Ok(response) if response.get_ref().success => {
            let response = response.into_inner();
            inputs.status = Some(tr!(
                Locale::from_headers(&headers),
                "td-profile-copied",
                "message" => response.message.clone(),
                "tables" => response.tables_copied as i64,
                "scripts" => response.scripts_copied as i64,
            ));
            inputs.copy = CopyForm {
                profile: form.profile,
                ..Default::default()
            };
            respond(state, headers, inputs, Page::Copy, StatusCode::OK).await
        }
        Ok(response) => {
            let message = response.into_inner().message;
            let message = if message.is_empty() {
                tr!(
                    Locale::from_headers(&headers),
                    "td-err-backend-no-copy"
                )
            } else {
                message
            };
            refuse(state, headers, inputs, Page::Copy, message).await
        }
        Err(error) => refuse(state, headers, inputs, Page::Copy, error.message().to_string()).await,
    }
}

/// POST /admin/tables/from-template — CreateInvoiceTemplateTable.
pub(crate) async fn create_from_invoice_template(
    State(state): State<AppState>,
    headers: HeaderMap,
    Form(form): Form<InvoiceTemplateForm>,
) -> Response {
    if let Some(rejection) = reject_cross_site(&headers) {
        return rejection;
    }

    let mut inputs = PageInputs::for_selection(Selection {
        profile: form.profile.clone(),
        table: String::new(),
    });
    inputs.invoice = form.clone();

    if form.table_name.trim().is_empty() || form.typst_source.trim().is_empty() {
        let message = tr!(
            Locale::from_headers(&headers),
            "td-err-template-required"
        );
        return refuse(
            state,
            headers,
            inputs,
            Page::Template,
            message,
        )
        .await;
    }

    let request = CreateInvoiceTemplateTableRequest {
        profile_name: form.profile.clone(),
        table_name: form.table_name.trim().to_string(),
        typst_source: form.typst_source.clone(),
        row_display_columns: form.display_columns(),
    };
    let Ok(request) = authenticated_request(&headers, request) else {
        return Redirect::to("/login").into_response();
    };

    let mut definitions = state.definitions.clone();
    match definitions.create_invoice_template_table(request).await {
        Ok(response) if response.get_ref().success => {
            let response = response.into_inner();
            inputs.status = Some(tr!(
                Locale::from_headers(&headers),
                "td-template-tables-created",
                "count" => response.tables.len() as i64,
            ));
            inputs.generated = response
                .tables
                .into_iter()
                .map(|table| GeneratedTableView {
                    table_name: table.table_name,
                    collection_path: table.collection_path,
                    parent_table_name: table.parent_table_name,
                })
                .collect();
            inputs.invoice = InvoiceTemplateForm {
                profile: form.profile,
                ..Default::default()
            };
            respond(state, headers, inputs, Page::Template, StatusCode::OK).await
        }
        Ok(_) => {
            let message = tr!(
                Locale::from_headers(&headers),
                "td-err-backend-no-template"
            );
            refuse(
                state,
                headers,
                inputs,
                Page::Template,
                message,
            )
            .await
        }
        Err(error) => {
            refuse(state, headers, inputs, Page::Template, error.message().to_string()).await
        }
    }
}

/// Re-reads the page's body and answers with it.
async fn respond(
    state: AppState,
    headers: HeaderMap,
    inputs: PageInputs,
    page: Page,
    status: StatusCode,
) -> Response {
    match load_page(state, &headers, inputs).await {
        Ok(mut loaded) => {
            loaded.active = page.name();
            (status, Html(page.render_fragment(&loaded))).into_response()
        }
        Err(error) => load_error_response(&headers, error),
    }
}

/// Answers a refused write: the page as it still is, plus the reason.
async fn refuse(
    state: AppState,
    headers: HeaderMap,
    mut inputs: PageInputs,
    page: Page,
    message: String,
) -> Response {
    inputs.error = Some(message);
    respond(state, headers, inputs, page, StatusCode::UNPROCESSABLE_ENTITY).await
}

fn load_error_response(headers: &HeaderMap, error: LoadError) -> Response {
    match error {
        LoadError::Unauthenticated => Redirect::to("/login").into_response(),
        LoadError::Forbidden => (
            StatusCode::FORBIDDEN,
            Html(ui::render_load_error(
                Locale::from_headers(headers),
                &tr!(
                    Locale::from_headers(headers),
                    "td-err-permission"
                ),
            )),
        )
            .into_response(),
        LoadError::Backend(message) => (
            StatusCode::BAD_GATEWAY,
            Html(ui::render_load_error(Locale::from_headers(headers), &message)),
        )
            .into_response(),
    }
}