use serde_json::{json, Value};

use crate::dispatch::CdpContext;
use crate::types::CdpEvent;
use crate::util::url_is_file_scheme;

pub async fn handle(method: &str, params: &Value, ctx: &mut CdpContext) -> Result<Value, String> {
    match method {
        "setDiscoverTargets" => {
            ctx.pending_events.push(CdpEvent::new(
                "Target.targetCreated",
                json!({
                    "targetInfo": {
                        "targetId": "browser",
                        "type": "browser",
                        "title": "",
                        "url": "",
                        "attached": true,
                        "canAccessOpener": false,
                        "browserContextId": "",
                    }
                }),
            ));
            for page in &ctx.pages {
                ctx.pending_events.push(CdpEvent::new(
                    "Target.targetCreated",
                    json!({
                        "targetInfo": {
                            "targetId": page.id,
                            "type": "page",
                            "title": page.title,
                            "url": page.url_string(),
                            "attached": false,
                            "canAccessOpener": false,
                            "browserContextId": page.context.id,
                        }
                    }),
                ));
            }
            Ok(json!({}))
        }
        "getTargets" => {
            let targets: Vec<Value> = ctx
                .pages
                .iter()
                .map(|page| {
                    json!({
                        "targetId": page.id,
                        "type": "page",
                        "title": page.title,
                        "url": page.url_string(),
                        "attached": true,
                        "canAccessOpener": false,
                        "browserContextId": page.context.id,
                    })
                })
                .collect();
            Ok(json!({ "targetInfos": targets }))
        }
        "createTarget" => {
            let url = params.get("url").and_then(|v| v.as_str()).unwrap_or("about:blank");

            // Same gate as Page.navigate (GHSA-q55h-vfv9-qcr5). Without this,
            // a CDP client can call Target.createTarget {url:"file:///etc/passwd"}
            // and then Runtime.evaluate the body off the created target,
            // bypassing the page-domain check entirely.
            if url_is_file_scheme(url) && !ctx.default_context.allow_file_access {
                return Err(
                    "Target.createTarget to file:// is disabled. Restart with `obscura serve --allow-file-access` to enable.".to_string()
                );
            }

            let page_id = ctx.create_page();
            let session_id = format!("{}-session", page_id);

            if let Some(page) = ctx.get_page_mut(&page_id) {
                if url == "about:blank" || url.is_empty() {
                    page.navigate_blank();
                } else {
                    let _ = page.navigate(url).await;
                }
            }

            ctx.sessions.insert(session_id.clone(), page_id.clone());

            if let Some(page) = ctx.get_page(&page_id) {
                ctx.pending_events.push(CdpEvent::new(
                    "Target.targetCreated",
                    json!({
                        "targetInfo": {
                            "targetId": page_id,
                            "type": "page",
                            "title": page.title,
                            "url": page.url_string(),
                            "attached": false,
                            "canAccessOpener": false,
                            "browserContextId": page.context.id,
                        }
                    }),
                ));
            }

            if let Some(page) = ctx.get_page(&page_id) {
                ctx.pending_events.push(CdpEvent::new(
                    "Target.attachedToTarget",
                    json!({
                        "sessionId": session_id,
                        "targetInfo": {
                            "targetId": page_id,
                            "type": "page",
                            "title": page.title,
                            "url": page.url_string(),
                            "attached": true,
                            "canAccessOpener": false,
                            "browserContextId": page.context.id,
                        },
                        "waitingForDebugger": false,
                    }),
                ));
            }

            Ok(json!({ "targetId": page_id }))
        }
        "attachToBrowserTarget" => {
            // Playwright calls this on connect to obtain a session for the
            // implicit "browser" target. Returning Unknown method aborts
            // the connect handshake before any user code runs.
            let session_id = "browser-session".to_string();
            ctx.sessions.insert(session_id.clone(), "browser".to_string());

            ctx.pending_events.push(CdpEvent::new(
                "Target.attachedToTarget",
                json!({
                    "sessionId": session_id,
                    "targetInfo": {
                        "targetId": "browser",
                        "type": "browser",
                        "title": "",
                        "url": "",
                        "attached": true,
                        "canAccessOpener": false,
                        "browserContextId": "",
                    },
                    "waitingForDebugger": false,
                }),
            ));

            Ok(json!({ "sessionId": session_id }))
        }
        "attachToTarget" => {
            let target_id = params.get("targetId").and_then(|v| v.as_str())
                .ok_or("targetId required")?;
            let session_id = format!("{}-session", target_id);
            ctx.sessions.insert(session_id.clone(), target_id.to_string());

            if let Some(page) = ctx.get_page(target_id) {
                ctx.pending_events.push(CdpEvent::new(
                    "Target.attachedToTarget",
                    json!({
                        "sessionId": session_id,
                        "targetInfo": {
                            "targetId": target_id,
                            "type": "page",
                            "title": page.title,
                            "url": page.url_string(),
                            "attached": true,
                            "canAccessOpener": false,
                            "browserContextId": page.context.id,
                        },
                        "waitingForDebugger": false,
                    }),
                ));
            }

            Ok(json!({ "sessionId": session_id }))
        }
        "closeTarget" => {
            let target_id = params.get("targetId").and_then(|v| v.as_str())
                .ok_or("targetId required")?;
            let session_id = format!("{}-session", target_id);

            ctx.pending_events.push(CdpEvent::new(
                "Target.detachedFromTarget",
                json!({
                    "sessionId": session_id,
                    "targetId": target_id,
                }),
            ));
            ctx.pending_events.push(CdpEvent::new(
                "Target.targetDestroyed",
                json!({ "targetId": target_id }),
            ));

            ctx.remove_page(target_id);
            Ok(json!({ "success": true }))
        }
        "setAutoAttach" => Ok(json!({})),
        "getBrowserContexts" => {
            Ok(json!({ "browserContextIds": [ctx.default_context.id] }))
        }
        "createBrowserContext" => {
            ctx.default_context.cookie_jar.clear();
            Ok(json!({ "browserContextId": ctx.default_context.id }))
        }
        "disposeBrowserContext" => {
            ctx.default_context.cookie_jar.clear();
            Ok(json!({}))
        }
        "getTargetInfo" => {
            let target_id = params.get("targetId").and_then(|v| v.as_str());
            match target_id {
                Some(id) => {
                    let page = ctx.get_page(id).ok_or("Target not found")?;
                    Ok(json!({
                        "targetInfo": {
                            "targetId": id,
                            "type": "page",
                            "title": page.title,
                            "url": page.url_string(),
                            "attached": true,
                            "canAccessOpener": false,
                            "browserContextId": page.context.id,
                        }
                    }))
                }
                None => {
                    // canAccessOpener is required on every TargetInfo per the
                    // CDP spec. Strict clients (chromiumoxide) panic if it's
                    // missing. The browser target itself has no opener.
                    Ok(json!({
                        "targetInfo": {
                            "targetId": "browser",
                            "type": "browser",
                            "title": "",
                            "url": "",
                            "attached": true,
                            "canAccessOpener": false,
                        }
                    }))
                }
            }
        }
        _ => Err(format!("Unknown Target method: {}", method)),
    }
}

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

    #[tokio::test]
    async fn attach_to_browser_target_returns_session_id() {
        let mut ctx = CdpContext::new();
        let result = handle("attachToBrowserTarget", &json!({}), &mut ctx)
            .await
            .expect("attachToBrowserTarget should succeed");

        assert_eq!(result["sessionId"], "browser-session");
        assert_eq!(
            ctx.sessions.get("browser-session").map(String::as_str),
            Some("browser")
        );

        // Playwright/Puppeteer expect a Target.attachedToTarget event before
        // they finish wiring up the session — without it the connect promise
        // hangs.
        let attached_evt = ctx
            .pending_events
            .iter()
            .find(|e| e.method == "Target.attachedToTarget")
            .expect("attachedToTarget event must be emitted");
        assert_eq!(attached_evt.params["sessionId"], "browser-session");
        assert_eq!(attached_evt.params["targetInfo"]["type"], "browser");
    }

    #[tokio::test]
    async fn unknown_target_method_still_errors() {
        let mut ctx = CdpContext::new();
        let err = handle("notARealMethod", &json!({}), &mut ctx)
            .await
            .expect_err("unknown methods must surface as errors");
        assert!(err.contains("Unknown Target method"));
    }

    /// Regression for #122 item 5: every TargetInfo payload must carry the
    /// `canAccessOpener` field. The browser-target branch of getTargetInfo
    /// (no targetId passed → no page) used to omit it; strict CDP clients
    /// like chromiumoxide panic when the field is missing.
    #[tokio::test]
    async fn get_target_info_browser_target_includes_can_access_opener() {
        let mut ctx = CdpContext::new();
        // No targetId → falls through to the browser-target branch.
        let result = handle("getTargetInfo", &json!({}), &mut ctx)
            .await
            .expect("getTargetInfo with no targetId must return browser info");

        let info = &result["targetInfo"];
        assert_eq!(info["type"], "browser", "must be the browser target");
        assert!(
            info.get("canAccessOpener").is_some(),
            "canAccessOpener must be present on every TargetInfo, got: {result}"
        );
        assert_eq!(info["canAccessOpener"], false);
    }
}