use std::collections::HashMap;

use serde_json::Value;

use super::cdp::client::CdpClient;
use super::cdp::types::*;

#[derive(Debug, Clone)]
pub struct RefEntry {
    pub backend_node_id: Option<i64>,
    pub role: String,
    pub name: String,
    pub nth: Option<usize>,
    pub selector: Option<String>,
}

pub struct RefMap {
    map: HashMap<String, RefEntry>,
    next_ref: usize,
}

impl RefMap {
    pub fn new() -> Self {
        Self {
            map: HashMap::new(),
            next_ref: 1,
        }
    }

    pub fn add(
        &mut self,
        ref_id: String,
        backend_node_id: Option<i64>,
        role: &str,
        name: &str,
        nth: Option<usize>,
    ) {
        self.map.insert(
            ref_id,
            RefEntry {
                backend_node_id,
                role: role.to_string(),
                name: name.to_string(),
                nth,
                selector: None,
            },
        );
    }

    pub fn get(&self, ref_id: &str) -> Option<&RefEntry> {
        self.map.get(ref_id)
    }

    pub fn clear(&mut self) {
        self.map.clear();
        self.next_ref = 1;
    }

    pub fn next_ref_num(&self) -> usize {
        self.next_ref
    }

    pub fn set_next_ref_num(&mut self, n: usize) {
        self.next_ref = n;
    }
}

pub fn parse_ref(input: &str) -> Option<String> {
    let trimmed = input.trim();

    if let Some(stripped) = trimmed.strip_prefix('@') {
        if stripped.starts_with('e') && stripped[1..].chars().all(|c| c.is_ascii_digit()) {
            return Some(stripped.to_string());
        }
    }

    if let Some(stripped) = trimmed.strip_prefix("ref=") {
        if stripped.starts_with('e') && stripped[1..].chars().all(|c| c.is_ascii_digit()) {
            return Some(stripped.to_string());
        }
    }

    if trimmed.starts_with('e')
        && trimmed.len() > 1
        && trimmed[1..].chars().all(|c| c.is_ascii_digit())
    {
        return Some(trimmed.to_string());
    }

    None
}

pub async fn resolve_element_center(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<(f64, f64), String> {
    if let Some(ref_id) = parse_ref(selector_or_ref) {
        let entry = ref_map
            .get(&ref_id)
            .ok_or_else(|| format!("Unknown ref: {}", ref_id))?;

        if let Some(backend_node_id) = entry.backend_node_id {
            let result: DomGetBoxModelResult = client
                .send_command_typed(
                    "DOM.getBoxModel",
                    &DomGetBoxModelParams {
                        backend_node_id: Some(backend_node_id),
                        node_id: None,
                        object_id: None,
                    },
                    Some(session_id),
                )
                .await?;

            return Ok(box_model_center(&result.model));
        }

        // Fallback: use role/name to find via JS
        return resolve_by_role_name(client, session_id, &entry.role, &entry.name, entry.nth).await;
    }

    // CSS selector
    resolve_by_selector(client, session_id, selector_or_ref).await
}

pub async fn resolve_element_object_id(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<String, String> {
    if let Some(ref_id) = parse_ref(selector_or_ref) {
        let entry = ref_map
            .get(&ref_id)
            .ok_or_else(|| format!("Unknown ref: {}", ref_id))?;

        if let Some(backend_node_id) = entry.backend_node_id {
            let result: DomResolveNodeResult = client
                .send_command_typed(
                    "DOM.resolveNode",
                    &DomResolveNodeParams {
                        backend_node_id: Some(backend_node_id),
                        node_id: None,
                        object_group: Some("agent-browser".to_string()),
                    },
                    Some(session_id),
                )
                .await?;

            return result
                .object
                .object_id
                .ok_or_else(|| format!("No objectId for ref {}", ref_id));
        }
    }

    // CSS selector fallback
    let js = format!(
        "document.querySelector({})",
        serde_json::to_string(selector_or_ref).unwrap_or_default()
    );
    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.evaluate",
            &EvaluateParams {
                expression: js,
                return_by_value: Some(false),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    result
        .result
        .object_id
        .ok_or_else(|| format!("Element not found: {}", selector_or_ref))
}

async fn resolve_by_role_name(
    client: &CdpClient,
    session_id: &str,
    role: &str,
    name: &str,
    nth: Option<usize>,
) -> Result<(f64, f64), String> {
    let nth_index = nth.unwrap_or(0);
    let js = format!(
        r#"(() => {{
            const walker = document.createTreeWalker(document.body, NodeFilter.SHOW_ELEMENT);
            const matches = [];
            let node;
            while (node = walker.nextNode()) {{
                const r = node.getAttribute('role') || node.tagName.toLowerCase();
                const n = node.getAttribute('aria-label') || node.textContent.trim().slice(0, 100);
                if (r === {role} && n === {name}) matches.push(node);
            }}
            const el = matches[{nth}];
            if (!el) return null;
            const rect = el.getBoundingClientRect();
            return {{ x: rect.x + rect.width / 2, y: rect.y + rect.height / 2 }};
        }})()"#,
        role = serde_json::to_string(role).unwrap_or_default(),
        name = serde_json::to_string(name).unwrap_or_default(),
        nth = nth_index,
    );

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.evaluate",
            &EvaluateParams {
                expression: js,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    let val = result.result.value.unwrap_or(Value::Null);
    let x = val.get("x").and_then(|v| v.as_f64());
    let y = val.get("y").and_then(|v| v.as_f64());

    match (x, y) {
        (Some(x), Some(y)) => Ok((x, y)),
        _ => Err(format!(
            "Could not locate element with role={} name={}",
            role, name
        )),
    }
}

async fn resolve_by_selector(
    client: &CdpClient,
    session_id: &str,
    selector: &str,
) -> Result<(f64, f64), String> {
    let js = format!(
        r#"(() => {{
            const el = document.querySelector({sel});
            if (!el) return null;
            const rect = el.getBoundingClientRect();
            return {{ x: rect.x + rect.width / 2, y: rect.y + rect.height / 2 }};
        }})()"#,
        sel = serde_json::to_string(selector).unwrap_or_default(),
    );

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.evaluate",
            &EvaluateParams {
                expression: js,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    let val = result.result.value.unwrap_or(Value::Null);
    let x = val.get("x").and_then(|v| v.as_f64());
    let y = val.get("y").and_then(|v| v.as_f64());

    match (x, y) {
        (Some(x), Some(y)) => Ok((x, y)),
        _ => Err(format!("Element not found: {}", selector)),
    }
}

fn box_model_center(model: &BoxModel) -> (f64, f64) {
    // content quad: [x1,y1, x2,y2, x3,y3, x4,y4]
    if model.content.len() >= 8 {
        let x = (model.content[0] + model.content[2] + model.content[4] + model.content[6]) / 4.0;
        let y = (model.content[1] + model.content[3] + model.content[5] + model.content[7]) / 4.0;
        (x, y)
    } else {
        (0.0, 0.0)
    }
}

pub async fn get_element_text(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<String, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration:
                    "function() { return this.innerText || this.textContent || ''; }".to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_str().map(|s| s.to_string()))
        .unwrap_or_default())
}

pub async fn get_element_attribute(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
    attribute: &str,
) -> Result<Value, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: format!(
                    "function() {{ return this.getAttribute({}); }}",
                    serde_json::to_string(attribute).unwrap_or_default()
                ),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result.result.value.unwrap_or(Value::Null))
}

pub async fn is_element_visible(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<bool, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: r#"function() {
                    const rect = this.getBoundingClientRect();
                    const style = window.getComputedStyle(this);
                    return rect.width > 0 && rect.height > 0 &&
                           style.visibility !== 'hidden' &&
                           style.display !== 'none' &&
                           parseFloat(style.opacity) > 0;
                }"#
                .to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_bool())
        .unwrap_or(false))
}

pub async fn is_element_enabled(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<bool, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: "function() { return !this.disabled; }".to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_bool())
        .unwrap_or(true))
}

pub async fn is_element_checked(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<bool, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: "function() { return !!this.checked; }".to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_bool())
        .unwrap_or(false))
}

pub async fn get_element_inner_text(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<String, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: "function() { return this.innerText || ''; }".to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_str().map(|s| s.to_string()))
        .unwrap_or_default())
}

pub async fn get_element_inner_html(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<String, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: "function() { return this.innerHTML || ''; }".to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_str().map(|s| s.to_string()))
        .unwrap_or_default())
}

pub async fn get_element_input_value(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<String, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration:
                    "function() { return typeof this.value === 'string' ? this.value : ''; }"
                        .to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result
        .result
        .value
        .and_then(|v| v.as_str().map(|s| s.to_string()))
        .unwrap_or_default())
}

pub async fn set_element_value(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
    value: &str,
) -> Result<(), String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let js = format!(
        "function() {{ this.value = {}; this.dispatchEvent(new Event('input', {{bubbles: true}})); this.dispatchEvent(new Event('change', {{bubbles: true}})); }}",
        serde_json::to_string(value).unwrap_or_default()
    );

    client
        .send_command_typed::<_, EvaluateResult>(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: js,
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(())
}

pub async fn get_element_bounding_box(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
) -> Result<Value, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: r#"function() {
                    const r = this.getBoundingClientRect();
                    return { x: r.x, y: r.y, width: r.width, height: r.height };
                }"#
                .to_string(),
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    result
        .result
        .value
        .ok_or_else(|| format!("Could not get bounding box for: {}", selector_or_ref))
}

pub async fn get_element_count(
    client: &CdpClient,
    session_id: &str,
    selector: &str,
) -> Result<i64, String> {
    let js = format!(
        "document.querySelectorAll({}).length",
        serde_json::to_string(selector).unwrap_or_default()
    );

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.evaluate",
            &EvaluateParams {
                expression: js,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result.result.value.and_then(|v| v.as_i64()).unwrap_or(0))
}

pub async fn get_element_styles(
    client: &CdpClient,
    session_id: &str,
    ref_map: &RefMap,
    selector_or_ref: &str,
    properties: Option<Vec<String>>,
) -> Result<Value, String> {
    let object_id = resolve_element_object_id(client, session_id, ref_map, selector_or_ref).await?;

    let js = match properties {
        Some(props) => {
            let props_json = serde_json::to_string(&props).unwrap_or("[]".to_string());
            format!(
                r#"function() {{
                    const s = window.getComputedStyle(this);
                    const props = {};
                    const result = {{}};
                    for (const p of props) result[p] = s.getPropertyValue(p);
                    return result;
                }}"#,
                props_json
            )
        }
        None => r#"function() {
                    const s = window.getComputedStyle(this);
                    const result = {};
                    for (let i = 0; i < s.length; i++) {
                        const p = s[i];
                        result[p] = s.getPropertyValue(p);
                    }
                    return result;
                }"#
        .to_string(),
    };

    let result: EvaluateResult = client
        .send_command_typed(
            "Runtime.callFunctionOn",
            &CallFunctionOnParams {
                function_declaration: js,
                object_id: Some(object_id),
                arguments: None,
                return_by_value: Some(true),
                await_promise: Some(false),
            },
            Some(session_id),
        )
        .await?;

    Ok(result.result.value.unwrap_or(Value::Null))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_ref_at_prefix() {
        assert_eq!(parse_ref("@e1"), Some("e1".to_string()));
        assert_eq!(parse_ref("@e123"), Some("e123".to_string()));
    }

    #[test]
    fn test_parse_ref_equals_prefix() {
        assert_eq!(parse_ref("ref=e1"), Some("e1".to_string()));
    }

    #[test]
    fn test_parse_ref_bare() {
        assert_eq!(parse_ref("e1"), Some("e1".to_string()));
        assert_eq!(parse_ref("e42"), Some("e42".to_string()));
    }

    #[test]
    fn test_parse_ref_invalid() {
        assert_eq!(parse_ref("button"), None);
        assert_eq!(parse_ref("e"), None);
        assert_eq!(parse_ref("1"), None);
        assert_eq!(parse_ref(""), None);
    }

    #[test]
    fn test_ref_map_basic() {
        let mut map = RefMap::new();
        map.add("e1".to_string(), Some(42), "button", "Submit", None);
        assert!(map.get("e1").is_some());
        assert_eq!(map.get("e1").unwrap().role, "button");
        assert!(map.get("e2").is_none());
    }

    #[test]
    fn test_box_model_center() {
        let model = BoxModel {
            content: vec![10.0, 20.0, 110.0, 20.0, 110.0, 60.0, 10.0, 60.0],
            padding: vec![],
            border: vec![],
            margin: vec![],
            width: 100,
            height: 40,
        };
        let (x, y) = box_model_center(&model);
        assert!((x - 60.0).abs() < 0.01);
        assert!((y - 40.0).abs() < 0.01);
    }
}