//! Backlinks panel component for showing incoming links to a note.

use dioxus::prelude::*;

use crate::client::{ApiClient, BacklinkItem, BacklinksResponse};

/// Panel displaying backlinks (incoming links) to a media item.
#[component]
pub fn BacklinksPanel(
    media_id: String,
    client: ApiClient,
    on_navigate: EventHandler<String>,
) -> Element {
    let mut backlinks = use_signal(|| Option::<BacklinksResponse>::None);
    let mut loading = use_signal(|| true);
    let mut error = use_signal(|| Option::<String>::None);
    let mut collapsed = use_signal(|| false);
    let mut reindexing = use_signal(|| false);
    let mut reindex_message = use_signal(|| Option::<(String, bool)>::None); // (message, is_error)

    // Fetch backlinks function
    let fetch_backlinks = {
        let client = client.clone();
        let id = media_id.clone();
        move || {
            let client = client.clone();
            let id = id.clone();
            spawn(async move {
                loading.set(true);
                error.set(None);
                match client.get_backlinks(&id).await {
                    Ok(resp) => {
                        backlinks.set(Some(resp));
                    }
                    Err(e) => {
                        error.set(Some(format!("Failed to load backlinks: {e}")));
                    }
                }
                loading.set(false);
            });
        }
    };

    // Fetch backlinks on mount
    let fetch_on_mount = fetch_backlinks.clone();
    use_effect(move || {
        fetch_on_mount();
    });

    // Reindex links handler
    let on_reindex = {
        let client = client.clone();
        let id = media_id.clone();
        let fetch_backlinks = fetch_backlinks.clone();
        move |evt: MouseEvent| {
            evt.stop_propagation(); // Don't toggle collapse
            let client = client.clone();
            let id = id.clone();
            let fetch_backlinks = fetch_backlinks.clone();
            spawn(async move {
                reindexing.set(true);
                reindex_message.set(None);
                match client.reindex_links(&id).await {
                    Ok(resp) => {
                        reindex_message.set(Some((
                            format!("Reindexed: {} links extracted", resp.links_extracted),
                            false,
                        )));
                        // Refresh backlinks after reindex
                        fetch_backlinks();
                    }
                    Err(e) => {
                        reindex_message.set(Some((format!("Reindex failed: {e}"), true)));
                    }
                }
                reindexing.set(false);
            });
        }
    };

    let is_loading = *loading.read();
    let is_collapsed = *collapsed.read();
    let is_reindexing = *reindexing.read();
    let backlink_data = backlinks.read();
    let count = backlink_data.as_ref().map(|b| b.count).unwrap_or(0);

    rsx! {
        div { class: "backlinks-panel",
            // Header with toggle
            div {
                class: "backlinks-header",
                onclick: move |_| {
                    let current = *collapsed.read();
                    collapsed.set(!current);
                },
                span { class: "backlinks-toggle",
                    if is_collapsed { "\u{25b6}" } else { "\u{25bc}" }
                }
                span { class: "backlinks-title", "Backlinks" }
                span { class: "backlinks-count", "({count})" }
                // Reindex button
                button {
                    class: "backlinks-reindex-btn",
                    title: "Re-extract links from this note",
                    disabled: is_reindexing,
                    onclick: on_reindex,
                    if is_reindexing {
                        span { class: "spinner-tiny" }
                    } else {
                        "\u{21bb}" // Refresh symbol
                    }
                }
            }

            if !is_collapsed {
                div { class: "backlinks-content",
                    // Show reindex message if present
                    if let Some((ref msg, is_err)) = *reindex_message.read() {
                        div {
                            class: if is_err { "backlinks-message error" } else { "backlinks-message success" },
                            "{msg}"
                        }
                    }

                    if is_loading {
                        div { class: "backlinks-loading",
                            div { class: "spinner-small" }
                            "Loading backlinks..."
                        }
                    }

                    if let Some(ref err) = *error.read() {
                        div { class: "backlinks-error", "{err}" }
                    }

                    if !is_loading && error.read().is_none() {
                        if let Some(ref data) = *backlink_data {
                            if data.backlinks.is_empty() {
                                div { class: "backlinks-empty",
                                    "No other notes link to this one."
                                }
                            } else {
                                ul { class: "backlinks-list",
                                    for backlink in &data.backlinks {
                                        BacklinkItemView {
                                            backlink: backlink.clone(),
                                            on_navigate: on_navigate.clone(),
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

/// Individual backlink item view.
#[component]
fn BacklinkItemView(
    backlink: BacklinkItem,
    on_navigate: EventHandler<String>,
) -> Element {
    let source_id = backlink.source_id.clone();
    let title = backlink
        .source_title
        .clone()
        .unwrap_or_else(|| backlink.source_path.clone());
    let context = backlink.context.clone();
    let line_number = backlink.line_number;
    let link_type = backlink.link_type.clone();

    rsx! {
        li {
            class: "backlink-item",
            onclick: move |_| on_navigate.call(source_id.clone()),
            div { class: "backlink-source",
                span { class: "backlink-title", "{title}" }
                span { class: "backlink-type-badge backlink-type-{link_type}", "{link_type}" }
            }
            if let Some(ref ctx) = context {
                div { class: "backlink-context",
                    if let Some(ln) = line_number {
                        span { class: "backlink-line", "L{ln}: " }
                    }
                    "\"{ctx}\""
                }
            }
        }
    }
}

/// Outgoing links panel showing what this note links to.
#[component]
pub fn OutgoingLinksPanel(
    media_id: String,
    client: ApiClient,
    on_navigate: EventHandler<String>,
) -> Element {
    let mut links = use_signal(|| Option::<crate::client::OutgoingLinksResponse>::None);
    let mut loading = use_signal(|| true);
    let mut error = use_signal(|| Option::<String>::None);
    let mut collapsed = use_signal(|| true); // Collapsed by default
    let mut global_unresolved = use_signal(|| Option::<u64>::None);

    // Fetch outgoing links on mount
    let id = media_id.clone();
    let client_clone = client.clone();
    use_effect(move || {
        let id = id.clone();
        let client = client_clone.clone();
        spawn(async move {
            loading.set(true);
            error.set(None);
            match client.get_outgoing_links(&id).await {
                Ok(resp) => {
                    links.set(Some(resp));
                }
                Err(e) => {
                    error.set(Some(format!("Failed to load links: {e}")));
                }
            }
            loading.set(false);

            // Also fetch global unresolved count
            if let Ok(count) = client.get_unresolved_links_count().await {
                global_unresolved.set(Some(count));
            }
        });
    });

    let is_loading = *loading.read();
    let is_collapsed = *collapsed.read();
    let link_data = links.read();
    let count = link_data.as_ref().map(|l| l.count).unwrap_or(0);
    let unresolved_in_note = link_data
        .as_ref()
        .map(|l| l.links.iter().filter(|link| !link.is_resolved).count())
        .unwrap_or(0);

    rsx! {
        div { class: "outgoing-links-panel",
            // Header with toggle
            div {
                class: "outgoing-links-header",
                onclick: move |_| {
                    let current = *collapsed.read();
                    collapsed.set(!current);
                },
                span { class: "outgoing-links-toggle",
                    if is_collapsed { "\u{25b6}" } else { "\u{25bc}" }
                }
                span { class: "outgoing-links-title", "Outgoing Links" }
                span { class: "outgoing-links-count", "({count})" }
                if unresolved_in_note > 0 {
                    span {
                        class: "outgoing-links-unresolved-badge",
                        title: "Unresolved links in this note",
                        "{unresolved_in_note} unresolved"
                    }
                }
            }

            if !is_collapsed {
                div { class: "outgoing-links-content",
                    if is_loading {
                        div { class: "outgoing-links-loading",
                            div { class: "spinner-small" }
                            "Loading links..."
                        }
                    }

                    if let Some(ref err) = *error.read() {
                        div { class: "outgoing-links-error", "{err}" }
                    }

                    if !is_loading && error.read().is_none() {
                        if let Some(ref data) = *link_data {
                            if data.links.is_empty() {
                                div { class: "outgoing-links-empty",
                                    "This note has no outgoing links."
                                }
                            } else {
                                ul { class: "outgoing-links-list",
                                    for link in &data.links {
                                        OutgoingLinkItemView {
                                            link: link.clone(),
                                            on_navigate: on_navigate.clone(),
                                        }
                                    }
                                }
                            }
                        }

                        // Show global unresolved count if any
                        if let Some(global_count) = *global_unresolved.read() {
                            if global_count > 0 {
                                div { class: "outgoing-links-global-unresolved",
                                    span { class: "unresolved-icon", "\u{26a0}" }
                                    " {global_count} unresolved links across all notes"
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

/// Individual outgoing link item view.
#[component]
fn OutgoingLinkItemView(
    link: crate::client::OutgoingLinkItem,
    on_navigate: EventHandler<String>,
) -> Element {
    let target_id = link.target_id.clone();
    let target_path = link.target_path.clone();
    let link_text = link.link_text.clone();
    let is_resolved = link.is_resolved;
    let link_type = link.link_type.clone();

    let display_text = link_text.unwrap_or_else(|| target_path.clone());
    let resolved_class = if is_resolved { "resolved" } else { "unresolved" };

    rsx! {
        li {
            class: "outgoing-link-item {resolved_class}",
            onclick: move |_| {
                if let Some(ref id) = target_id {
                    on_navigate.call(id.clone());
                }
            },
            div { class: "outgoing-link-target",
                span { class: "outgoing-link-text", "{display_text}" }
                span { class: "outgoing-link-type-badge link-type-{link_type}", "{link_type}" }
                if !is_resolved {
                    span { class: "unresolved-badge", "unresolved" }
                }
            }
        }
    }
}