use std::sync::Arc;
// tools/web.rs — Web fetch and search

use anyhow::{Context, Result};
use serde::Deserialize;
use html2md::parse_html;

pub fn tools() -> Vec<super::Tool> {
    let mut tools = vec![
        super::Tool {
            name: "web_fetch",
            description: "Fetch content from a URL and return it as text. Use for reading web pages, API responses, documentation.",
            parameters_json: r#"{"type":"object","properties":{"url":{"type":"string","description":"The URL to fetch"}},"required":["url"]}"#,
            handler: Arc::new(|_a, v| Box::pin(async move { web_fetch(&v).await })),
        },
        super::Tool {
            name: "web_search",
            description: "Search the web via DuckDuckGo and return a list of results (title, URL, snippet). Use for finding documentation, looking up APIs, researching topics. Returns raw results you can reason over yourself.",
            parameters_json: r#"{"type":"object","properties":{"query":{"type":"string","description":"The search query"},"num_results":{"type":"integer","description":"Number of results to return (default 5)"}},"required":["query"]}"#,
            handler: Arc::new(|_a, v| Box::pin(async move { web_search(&v).await })),
        },
    ];
    // Gemini-grounded search (Google's index via Gemini's google_search tool)
    // is only available if GEMINI_API_KEY is set. Returns an LLM-summarized
    // answer with source URLs — use when you want a synthesized take rather
    // than raw results, or as a fallback when DDG is flaky.
    if std::env::var("GEMINI_API_KEY").is_ok() {
        tools.push(super::Tool {
            name: "gemini_search",
            description: "Search Google (via Gemini's grounded-search tool) and return an LLM-summarized answer with source URLs. Prefer web_search for raw results; use this for synthesis, 'what's the consensus on X', or when DDG fails. Free-tier rate limited; don't spam it.",
            parameters_json: r#"{"type":"object","properties":{"query":{"type":"string","description":"The search query"}},"required":["query"]}"#,
            handler: Arc::new(|_a, v| Box::pin(async move { gemini_search(&v).await })),
        });
    }
    tools
}

#[derive(Deserialize)]
struct FetchArgs { url: String }

async fn web_fetch(args: &serde_json::Value) -> Result<String> {
    let a: FetchArgs = serde_json::from_value(args.clone())
        .context("invalid web_fetch arguments")?;

    let client = http_client();
    let response = client.get_with_headers(&a.url, &[
        ("user-agent", "consciousness/0.3"),
    ]).await
        .with_context(|| format!("failed to fetch {}", a.url))?;

    let status = response.status();
    if !status.is_success() {
        anyhow::bail!("HTTP {}: {}", status, a.url);
    }

    let body = response.text().await
        .with_context(|| format!("failed to read body from {}", a.url))?;

    // Convert HTML to Markdown, then truncate
    let markdown = parse_html(&body);
    Ok(super::truncate_output(markdown, 30000))
}

// ── Search ──────────────────────────────────────────────────────

#[derive(Deserialize)]
struct SearchArgs {
    query: String,
    #[serde(default = "default_num_results")]
    num_results: usize,
}

fn default_num_results() -> usize { 5 }

async fn web_search(args: &serde_json::Value) -> Result<String> {
    let a: SearchArgs = serde_json::from_value(args.clone())
        .context("invalid web_search arguments")?;

    // Use DuckDuckGo HTML search — no API key needed
    let client = http_client();
    let encoded: String = a.query.chars().map(|c| {
        if c.is_ascii_alphanumeric() || c == '-' || c == '_' || c == '.' {
            c.to_string()
        } else if c == ' ' {
            "+".to_string()
        } else {
            format!("%{:02X}", c as u32)
        }
    }).collect();
    let url = format!("https://html.duckduckgo.com/html/?q={}", encoded);
    let response = client.get_with_headers(&url, &[
        ("user-agent", "consciousness/0.3"),
    ]).await
        .context("search request failed")?;

    let body = response.text().await
        .context("failed to read search results")?;

    // Extract result snippets from DDG HTML
    let mut results = Vec::new();
    for chunk in body.split("class=\"result__body\"") {
        if results.len() >= a.num_results { break; }
        if results.is_empty() && !chunk.contains("result__title") {
            continue;
        }

        let title = extract_between(chunk, "class=\"result__a\"", "</a>")
            .map(strip_tags)
            .unwrap_or_default();

        let href = extract_between(chunk, "href=\"", "\"")
            .unwrap_or_default();

        let snippet = extract_between(chunk, "class=\"result__snippet\"", "</a>")
            .map(strip_tags)
            .unwrap_or_default();

        if !title.is_empty() {
            results.push(format!("{}. {}\n   {}\n   {}", results.len() + 1, title.trim(), href.trim(), snippet.trim()));
        }
    }

    if results.is_empty() {
        Ok(format!("No results found for: {}", a.query))
    } else {
        Ok(results.join("\n\n"))
    }
}

// ── Gemini grounded search ──────────────────────────────────────

#[derive(Deserialize)]
struct GeminiSearchArgs {
    query: String,
}

async fn gemini_search(args: &serde_json::Value) -> Result<String> {
    let a: GeminiSearchArgs = serde_json::from_value(args.clone())
        .context("invalid gemini_search arguments")?;

    let api_key = std::env::var("GEMINI_API_KEY")
        .context("GEMINI_API_KEY not set")?;

    // gemini-2.0-flash has a free tier with Google search grounding.
    // Request shape: `{"contents": [{"parts": [{"text": query}]}],
    //                 "tools": [{"google_search": {}}]}`.
    // Response carries the summary in candidates[0].content.parts[].text
    // and grounding URLs in candidates[0].groundingMetadata.groundingChunks[].web.
    let url = format!(
        "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key={}",
        api_key
    );
    let body = serde_json::json!({
        "contents": [{"parts": [{"text": a.query}]}],
        "tools": [{"google_search": {}}],
    });

    let client = http_client();
    let response = client.send_json("POST", &url, &[], &body).await
        .context("gemini API request failed")?;
    let status = response.status();
    if !status.is_success() {
        let err_body = response.text().await.unwrap_or_default();
        let n = err_body.floor_char_boundary(err_body.len().min(500));
        anyhow::bail!("gemini_search HTTP {}: {}", status, &err_body[..n]);
    }

    let parsed: GeminiResponse = response.json().await
        .context("gemini response parse failed")?;

    let candidate = parsed.candidates.into_iter().next()
        .context("gemini returned no candidates")?;

    let summary: String = candidate.content.parts.iter()
        .filter_map(|p| p.text.as_deref())
        .collect::<Vec<_>>()
        .join("");

    let mut out = summary.trim().to_string();

    if let Some(meta) = candidate.grounding_metadata {
        let sources: Vec<String> = meta.grounding_chunks.iter().enumerate()
            .filter_map(|(i, c)| c.web.as_ref().map(|w| {
                let title = w.title.as_deref().unwrap_or("(untitled)");
                let uri = w.uri.as_deref().unwrap_or("");
                format!("  [{}] {} — {}", i + 1, title, uri)
            }))
            .collect();
        if !sources.is_empty() {
            out.push_str("\n\nSources:\n");
            out.push_str(&sources.join("\n"));
        }
    }

    Ok(super::truncate_output(out, 30000))
}

#[derive(Deserialize)]
struct GeminiResponse {
    #[serde(default)]
    candidates: Vec<GeminiCandidate>,
}

#[derive(Deserialize)]
struct GeminiCandidate {
    content: GeminiContent,
    #[serde(rename = "groundingMetadata", default)]
    grounding_metadata: Option<GeminiGroundingMetadata>,
}

#[derive(Deserialize)]
struct GeminiContent {
    #[serde(default)]
    parts: Vec<GeminiPart>,
}

#[derive(Deserialize)]
struct GeminiPart {
    #[serde(default)]
    text: Option<String>,
}

#[derive(Deserialize)]
struct GeminiGroundingMetadata {
    #[serde(rename = "groundingChunks", default)]
    grounding_chunks: Vec<GeminiGroundingChunk>,
}

#[derive(Deserialize)]
struct GeminiGroundingChunk {
    #[serde(default)]
    web: Option<GeminiWebSource>,
}

#[derive(Deserialize)]
struct GeminiWebSource {
    #[serde(default)]
    uri: Option<String>,
    #[serde(default)]
    title: Option<String>,
}

// ── Helpers ─────────────────────────────────────────────────────

fn http_client() -> crate::agent::api::http::HttpClient {
    crate::agent::api::http::HttpClient::builder()
        .timeout(std::time::Duration::from_secs(30))
        .build()
}

fn extract_between<'a>(text: &'a str, start: &str, end: &str) -> Option<&'a str> {
    let start_idx = text.find(start)? + start.len();
    // Skip past the closing > of the start tag
    let rest = &text[start_idx..];
    let gt = rest.find('>')?;
    let content_start = start_idx + gt + 1;
    let content = &text[content_start..];
    let end_idx = content.find(end)?;
    Some(&content[..end_idx])
}

fn strip_tags(html: &str) -> String {
    let mut out = String::new();
    let mut in_tag = false;
    for ch in html.chars() {
        match ch {
            '<' => in_tag = true,
            '>' => in_tag = false,
            _ if !in_tag => out.push(ch),
            _ => {}
        }
    }
    out.replace("&amp;", "&")
        .replace("&lt;", "<")
        .replace("&gt;", ">")
        .replace("&quot;", "\"")
        .replace("&#x27;", "'")
}