formal-ai 0.275.0

//! Google Trends snapshot conversion and multilingual prompt cataloging.
//!
//! Issue #498 asks for an automated path from Google Trends into reviewable test
//! cases: take the top searches, turn each search into Formal AI requests, include
//! variants in every supported language, and answer them through the normal symbolic
//! engine. The module keeps the live-network part outside tests. A checked-in Trends
//! RSS snapshot is parsed into `data/seed/google-trends-snapshot.lino`; the catalog is
//! then a deterministic function of that seed and `FormalAiEngine`.
//!
//! The multilingual request wording is *data*, not code: the templates live in
//! `data/seed/google-trends-prompts.lino` and are expanded per topic (per the
//! no-hardcoded-language convention, #386). Adding a language or a request variation
//! is a change to that seed with no edit to this converter — the language set comes
//! from `supported_languages()`, so coverage generalizes automatically.

use std::error::Error;
use std::fmt::{self, Write as _};
use std::sync::OnceLock;

use crate::engine::FormalAiEngine;
use crate::seed::parser::{parse_lino, LinoNode};
use crate::seed::supported_languages;

/// How many Google Trends topics issue #498 requires the system to answer.
pub const GOOGLE_TRENDS_TOP_LIMIT: usize = 10;

const GOOGLE_TRENDS_SNAPSHOT_LINO: &str = include_str!("../data/seed/google-trends-snapshot.lino");
const GOOGLE_TRENDS_PROMPTS_LINO: &str = include_str!("../data/seed/google-trends-prompts.lino");

/// A parsed Google Trends RSS snapshot plus generated prompts and answers.
#[derive(Debug, Clone, PartialEq)]
pub struct GoogleTrendsCatalog {
    /// Snapshot source identifier.
    pub source: String,
    /// Original source URL.
    pub source_url: String,
    /// Google Trends geography code, e.g. `US`.
    pub geo: String,
    /// Google Trends locale used when collecting the feed.
    pub locale: String,
    /// ISO-like timestamp for when the checked-in snapshot was collected.
    pub collected_at: String,
    /// Ranked topics, capped at [`GOOGLE_TRENDS_TOP_LIMIT`] for issue #498.
    pub topics: Vec<GoogleTrendTopic>,
}

/// A ranked trend topic from Google Trends.
#[derive(Debug, Clone, PartialEq)]
pub struct GoogleTrendTopic {
    /// One-based rank in the feed.
    pub rank: usize,
    /// Search query/topic title.
    pub query: String,
    /// Google-provided approximate traffic label, e.g. `2000+`.
    pub approx_traffic: Option<String>,
    /// RSS publication date for the trend item.
    pub pub_date: Option<String>,
    /// News references attached by Google Trends.
    pub news_items: Vec<GoogleTrendNewsItem>,
    /// Prompt variants generated from this topic.
    pub prompts: Vec<GoogleTrendPromptVariant>,
    /// Answers for every generated prompt variant.
    pub answered: Vec<GoogleTrendPromptAnswer>,
}

/// One news item attached to a trend topic.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GoogleTrendNewsItem {
    /// News headline/title.
    pub title: String,
    /// Source publication.
    pub source: String,
    /// Article URL.
    pub url: String,
}

/// A request variation generated from a trend topic.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GoogleTrendPromptVariant {
    /// Language tag (`en`, `ru`, `hi`, `zh`).
    pub language: String,
    /// Stable variation key.
    pub variation_key: String,
    /// Natural-language request text.
    pub prompt: String,
}

impl GoogleTrendPromptVariant {
    /// Whether this request asks for Google Trends context.
    #[must_use]
    pub fn is_trends_context_request(&self) -> bool {
        self.variation_key == "trends_context"
    }
}

/// A prompt variant answered through the normal Formal AI engine.
#[derive(Debug, Clone, PartialEq)]
pub struct GoogleTrendPromptAnswer {
    /// Language tag for the prompt.
    pub language: String,
    /// Stable variation key for the prompt.
    pub variation_key: String,
    /// Prompt text sent to Formal AI.
    pub prompt: String,
    /// Engine intent classification.
    pub intent: String,
    /// Engine confidence.
    pub confidence: f32,
    /// Engine answer.
    pub answer: String,
    /// Standard trace/evidence links returned by the engine.
    pub evidence_links: Vec<String>,
}

/// Error returned when a Google Trends RSS feed cannot be converted.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum GoogleTrendsParseError {
    /// The feed contained no `<item>` records with titles.
    NoTopics,
}

impl fmt::Display for GoogleTrendsParseError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::NoTopics => formatter.write_str("Google Trends RSS feed contained no topics"),
        }
    }
}

impl Error for GoogleTrendsParseError {}

/// Convert a Google Trends RSS XML string into ranked topics.
///
/// This parser targets the documented RSS feed shape used by
/// `https://trends.google.com/trending/rss?geo=US`: `<item>` records with
/// `<title>`, `<ht:approx_traffic>`, `<pubDate>`, and nested `<ht:news_item>`
/// records. Tests stay offline by feeding a small RSS fixture through this path.
///
/// # Errors
///
/// Returns [`GoogleTrendsParseError::NoTopics`] when no item title can be found.
pub fn parse_google_trends_rss(
    rss_xml: &str,
    geo: &str,
    locale: &str,
) -> Result<GoogleTrendsCatalog, GoogleTrendsParseError> {
    let mut topics = Vec::new();
    for block in extract_blocks(rss_xml, "item") {
        let Some(query) = extract_text(block, "title") else {
            continue;
        };
        if query.trim().is_empty() {
            continue;
        }
        let news_items = extract_blocks(block, "ht:news_item")
            .into_iter()
            .filter_map(parse_news_item)
            .collect();
        topics.push(GoogleTrendTopic {
            rank: topics.len() + 1,
            query,
            approx_traffic: extract_text(block, "ht:approx_traffic"),
            pub_date: extract_text(block, "pubDate"),
            news_items,
            prompts: Vec::new(),
            answered: Vec::new(),
        });
    }

    if topics.is_empty() {
        return Err(GoogleTrendsParseError::NoTopics);
    }

    Ok(GoogleTrendsCatalog {
        source: "google_trends_rss".to_string(),
        source_url: format!("https://trends.google.com/trending/rss?geo={geo}"),
        geo: geo.to_string(),
        locale: locale.to_string(),
        collected_at: String::new(),
        topics,
    })
}

/// The deterministic issue-#498 catalog generated from the checked-in Trends snapshot.
#[must_use]
pub fn google_trends_catalog() -> GoogleTrendsCatalog {
    cached_catalog().clone()
}

/// Render a parsed Trends snapshot as seed Links Notation.
///
/// The refresh flow is:
///
/// ```text
/// curl -sL 'https://trends.google.com/trending/rss?geo=US&hl=ru' \
///   | cargo run --example issue_498_parse_google_trends_rss \
///   > data/seed/google-trends-snapshot.lino
/// ```
#[must_use]
pub fn render_google_trends_snapshot_lino(snapshot: &GoogleTrendsCatalog) -> String {
    let mut out = String::from("google_trends_snapshot\n");
    out.push_str("  record_type \"google_trends_snapshot\"\n");
    field(&mut out, 2, "source", &snapshot.source);
    field(&mut out, 2, "source_url", &snapshot.source_url);
    field(&mut out, 2, "geo", &snapshot.geo);
    field(&mut out, 2, "locale", &snapshot.locale);
    if !snapshot.collected_at.trim().is_empty() {
        field(&mut out, 2, "collected_at", &snapshot.collected_at);
    }
    for topic in snapshot.topics.iter().take(GOOGLE_TRENDS_TOP_LIMIT) {
        out.push_str("google_trend_topic\n");
        out.push_str("  record_type \"google_trend_topic\"\n");
        let _ = writeln!(out, "  rank \"{}\"", topic.rank);
        field(&mut out, 2, "query", &topic.query);
        if let Some(traffic) = &topic.approx_traffic {
            field(&mut out, 2, "approx_traffic", traffic);
        }
        if let Some(pub_date) = &topic.pub_date {
            field(&mut out, 2, "pub_date", pub_date);
        }
        for item in &topic.news_items {
            out.push_str("  news_item\n");
            out.push_str("    record_type \"google_trend_news_item\"\n");
            field(&mut out, 4, "title", &item.title);
            field(&mut out, 4, "source", &item.source);
            field(&mut out, 4, "url", &item.url);
        }
    }
    format!("{}\n", out.trim_end())
}

fn cached_catalog() -> &'static GoogleTrendsCatalog {
    static CATALOG: OnceLock<GoogleTrendsCatalog> = OnceLock::new();
    CATALOG.get_or_init(build_catalog)
}

fn build_catalog() -> GoogleTrendsCatalog {
    let mut catalog = load_seed_snapshot();
    catalog.topics.sort_by_key(|topic| topic.rank);
    catalog.topics.truncate(GOOGLE_TRENDS_TOP_LIMIT);

    let engine = FormalAiEngine;
    for topic in &mut catalog.topics {
        topic.prompts = prompt_variants_for_topic(&topic.query);
        topic.answered = topic
            .prompts
            .iter()
            .map(|prompt| {
                let answer = engine.answer(&prompt.prompt);
                GoogleTrendPromptAnswer {
                    language: prompt.language.clone(),
                    variation_key: prompt.variation_key.clone(),
                    prompt: prompt.prompt.clone(),
                    intent: answer.intent,
                    confidence: answer.confidence,
                    answer: collapse_whitespace(&answer.answer),
                    evidence_links: answer.evidence_links,
                }
            })
            .collect();
    }

    catalog
}

fn load_seed_snapshot() -> GoogleTrendsCatalog {
    let tree = parse_lino(GOOGLE_TRENDS_SNAPSHOT_LINO);
    let root = tree
        .children
        .iter()
        .find(|record| record.find_child_value("record_type") == "google_trends_snapshot");

    let mut catalog = GoogleTrendsCatalog {
        source: child_value(root, "source")
            .unwrap_or("google_trends_rss")
            .to_string(),
        source_url: child_value(root, "source_url")
            .unwrap_or("https://trends.google.com/trending/rss?geo=US")
            .to_string(),
        geo: child_value(root, "geo").unwrap_or("US").to_string(),
        locale: child_value(root, "locale").unwrap_or("ru").to_string(),
        collected_at: child_value(root, "collected_at")
            .unwrap_or_default()
            .to_string(),
        topics: Vec::new(),
    };

    for record in tree
        .children
        .iter()
        .filter(|record| record.find_child_value("record_type") == "google_trend_topic")
    {
        let rank = record
            .find_child_value("rank")
            .parse::<usize>()
            .unwrap_or(catalog.topics.len() + 1);
        let query = record.find_child_value("query").trim();
        if query.is_empty() {
            continue;
        }
        let news_items = record
            .children
            .iter()
            .filter(|child| child.find_child_value("record_type") == "google_trend_news_item")
            .map(|child| GoogleTrendNewsItem {
                title: child.find_child_value("title").to_string(),
                source: child.find_child_value("source").to_string(),
                url: child.find_child_value("url").to_string(),
            })
            .filter(|item| !item.title.trim().is_empty())
            .collect();

        catalog.topics.push(GoogleTrendTopic {
            rank,
            query: query.to_string(),
            approx_traffic: optional_child(record.find_child_value("approx_traffic")),
            pub_date: optional_child(record.find_child_value("pub_date")),
            news_items,
            prompts: Vec::new(),
            answered: Vec::new(),
        });
    }

    catalog
}

fn child_value<'a>(root: Option<&'a LinoNode>, name: &str) -> Option<&'a str> {
    root.map(|node| node.find_child_value(name))
        .filter(|value| !value.trim().is_empty())
}

fn optional_child(value: &str) -> Option<String> {
    let trimmed = value.trim();
    (!trimmed.is_empty()).then(|| trimmed.to_string())
}

/// A multilingual request template loaded from the prompt seed.
///
/// The natural-language pattern lives in `data/seed/google-trends-prompts.lino`
/// (per the no-hardcoded-language convention, #386); `{query}` is substituted with
/// the trending search term when the catalog is built.
#[derive(Debug, Clone, PartialEq, Eq)]
struct GoogleTrendPromptTemplate {
    language: String,
    variation_key: String,
    text: String,
}

/// The placeholder in a seeded template replaced by the trending search term.
const QUERY_PLACEHOLDER: &str = "{query}";

/// Expand every seeded prompt template for `search`, in `supported_languages()`
/// order and, within each language, in seed order.
///
/// Adding a language or a request variation is a data-only change to the prompt
/// seed — this converter iterates whatever the seed declares, so no Rust edit is
/// needed to extend catalog coverage.
fn prompt_variants_for_topic(search: &str) -> Vec<GoogleTrendPromptVariant> {
    let templates = prompt_templates();
    supported_languages()
        .iter()
        .flat_map(|language| {
            templates
                .iter()
                .filter(|template| template.language == *language)
                .map(|template| GoogleTrendPromptVariant {
                    language: template.language.clone(),
                    variation_key: template.variation_key.clone(),
                    prompt: template.text.replace(QUERY_PLACEHOLDER, search),
                })
                .collect::<Vec<_>>()
        })
        .collect()
}

/// The seeded prompt templates, parsed once from the prompt catalog seed.
fn prompt_templates() -> &'static [GoogleTrendPromptTemplate] {
    static TEMPLATES: OnceLock<Vec<GoogleTrendPromptTemplate>> = OnceLock::new();
    TEMPLATES.get_or_init(load_prompt_templates)
}

fn load_prompt_templates() -> Vec<GoogleTrendPromptTemplate> {
    let tree = parse_lino(GOOGLE_TRENDS_PROMPTS_LINO);
    tree.children
        .iter()
        .filter(|record| record.find_child_value("record_type") == "google_trend_prompt_template")
        .filter_map(|record| {
            let language = record.find_child_value("language").trim();
            let variation_key = record.find_child_value("variation").trim();
            let text = record.find_child_value("text");
            if language.is_empty() || variation_key.is_empty() || text.trim().is_empty() {
                return None;
            }
            Some(GoogleTrendPromptTemplate {
                language: language.to_string(),
                variation_key: variation_key.to_string(),
                text: text.to_string(),
            })
        })
        .collect()
}

fn parse_news_item(block: &str) -> Option<GoogleTrendNewsItem> {
    let title = extract_text(block, "ht:news_item_title")?;
    let source = extract_text(block, "ht:news_item_source").unwrap_or_default();
    let url = extract_text(block, "ht:news_item_url").unwrap_or_default();
    Some(GoogleTrendNewsItem { title, source, url })
}

fn extract_blocks<'a>(text: &'a str, tag: &str) -> Vec<&'a str> {
    let start_tag = format!("<{tag}>");
    let end_tag = format!("</{tag}>");
    let mut blocks = Vec::new();
    let mut offset = 0usize;

    while let Some(start) = text[offset..].find(&start_tag) {
        let content_start = offset + start + start_tag.len();
        let Some(end) = text[content_start..].find(&end_tag) else {
            break;
        };
        let content_end = content_start + end;
        blocks.push(&text[content_start..content_end]);
        offset = content_end + end_tag.len();
    }

    blocks
}

fn extract_text(text: &str, tag: &str) -> Option<String> {
    let start_tag = format!("<{tag}>");
    let end_tag = format!("</{tag}>");
    let content_start = text.find(&start_tag)? + start_tag.len();
    let content_end = content_start + text[content_start..].find(&end_tag)?;
    let raw = text[content_start..content_end].trim();
    if raw.is_empty() {
        return None;
    }
    Some(collapse_whitespace(&decode_xml_text(raw)))
}

fn decode_xml_text(raw: &str) -> String {
    let cdata = raw
        .strip_prefix("<![CDATA[")
        .and_then(|value| value.strip_suffix("]]>"))
        .unwrap_or(raw);
    cdata
        .replace("&amp;", "&")
        .replace("&lt;", "<")
        .replace("&gt;", ">")
        .replace("&quot;", "\"")
        .replace("&apos;", "'")
}

fn field(out: &mut String, indent: usize, name: &str, value: &str) {
    let spaces = " ".repeat(indent);
    let _ = writeln!(out, "{spaces}{name} \"{}\"", escape_lino_value(value));
}

fn escape_lino_value(value: &str) -> String {
    collapse_whitespace(value).replace('"', "'")
}

fn collapse_whitespace(value: &str) -> String {
    value.split_whitespace().collect::<Vec<_>>().join(" ")
}