use crate::request::{RequestContext, api::Pager};
use crate::ui::htmx::{Event, HTMXAttributes, SwapStrategy};
use crate::ui::prelude::*;
use maud::{PreEscaped, html};

/// Represents a search form with configurable options such as heading, placeholder, and CSS class.
pub struct Search {
    post_url: String,
    heading: Option<PreEscaped<String>>,
    placeholder: Option<String>,
    search_class: Option<String>,
}

impl Search {
    /// Creates a new `Search` instance with the specified post URL.
    ///
    /// # Arguments
    /// * `post_url` - The URL where the search form will send the POST request.
    ///
    /// # Returns
    /// A new `Search` instance with default settings.
    #[must_use]
    pub const fn new(post_url: String) -> Self {
        Self {
            heading: None,
            placeholder: None,
            post_url,
            search_class: None,
        }
    }

    /// Sets the placeholder text for the search input field.
    ///
    /// # Arguments
    /// * `placeholder` - The placeholder text to display in the search input.
    ///
    /// # Returns
    /// The updated `Search` instance.
    #[must_use]
    pub fn placeholder(mut self, placeholder: String) -> Self {
        self.placeholder = Some(placeholder);
        self
    }

    /// Sets the heading to be displayed above the search form.
    ///
    /// # Arguments
    /// * `heading` - The heading element to display.
    ///
    /// # Returns
    /// The updated `Search` instance.
    #[must_use]
    pub fn heading(mut self, heading: PreEscaped<String>) -> Self {
        self.heading = Some(heading);
        self
    }

    /// Sets the CSS class for the search input field.
    ///
    /// # Arguments
    /// * `class` - The CSS class to apply to the search input.
    ///
    /// # Returns
    /// The updated `Search` instance.
    #[must_use]
    pub fn search_class(mut self, class: String) -> Self {
        self.search_class = Some(class);
        self
    }

    /// Builds the HTML for search results based on the current page and query.
    ///
    /// # Arguments
    /// * `pager` - The `Pager` instance to paginate results.
    /// * `page` - The current page number.
    /// * `query` - The search query string.
    /// * `result_ui` - A function that transforms each result into HTML.
    ///
    /// # Returns
    /// The HTML string containing the search results.
    pub fn build_results<T>(
        &self,
        pager: Pager<T>,
        page: i64,
        query: &str,
        result_ui: impl Fn(&T) -> PreEscaped<String>,
    ) -> PreEscaped<String> {
        let results = pager.page(page as u64);
        let reslen = results.len();

        html! {

            @for res in results {
                (result_ui(res))
            }

            @if reslen as u64 == pager.items_per_page {
                (Div()
                    .hx_get(
                        &format!("{}?query={}&page={}", self.post_url, query, page+1)
                    ).hx_trigger(
                        Event::on_revealed()
                    ).hx_swap(SwapStrategy::outerHTML))
            };
        }
    }

    /// Builds the full response based on the context (HTMX or full HTML response).
    ///
    /// # Arguments
    /// * `ctx` - The request context, used to determine if HTMX is enabled.
    /// * `results` - The `Pager` instance containing the search results.
    /// * `page` - The current page number.
    /// * `query` - The search query string.
    /// * `result_ui` - A function that transforms each result into HTML.
    ///
    /// # Returns
    /// The HTML string containing either the HTMX response or full page content.
    pub fn build_response<T>(
        &self,
        ctx: &RequestContext,
        results: Pager<T>,
        page: i64,
        query: &str,
        result_ui: impl Fn(&T) -> PreEscaped<String>,
    ) -> PreEscaped<String> {
        if ctx.is_htmx {
            // Return HTMX Search elements
            self.build_results(results, page, query, result_ui)
        } else {
            // Return full rendered site
            let first_page = self.build_results(results, page, query, result_ui);
            self.build(query, first_page)
        }
    }

    /// Builds the full search form and first search page results.
    ///
    /// # Arguments
    /// * `query` - The search query string.
    /// * `first_page` - The HTML string containing the first page of search results.
    ///
    /// # Returns
    /// The HTML string containing the entire search form and results UI.
    #[must_use]
    pub fn build(&self, query: &str, first_page: PreEscaped<String>) -> PreEscaped<String> {
        let no_html = Nothing();
        html! {
            (self.heading.as_ref().unwrap_or_else(|| &no_html))
            input type="search" name="query"
            value=(query)
            placeholder=(self.placeholder.as_ref().unwrap_or(&"Search...".to_string())) hx-get=(self.post_url)
            hx-trigger="input changed delay:500ms, keyup[key=='Enter'], load"
            hx-target="#search_results" hx-push-url="true"
            class=(self.search_class.as_deref().unwrap_or_default()) {};

            div id="search_results" {
                @if !query.is_empty() {
                    (first_page)
                }
            };
        }
    }
}