/*
 * Runs in the **WebExtension (addon)** context.
 * For this minimal working version we only expose an async helper
 * so UI pages / devtools panels can test the classifier without
 * needing Thunderbird’s filter engine.
 *
 * Note: the filter-engine itself NEVER calls this file – the
 * synchronous work is all done in experiment/api.js (chrome side).
 */

"use strict";

const storage = (globalThis.messenger ?? browser).storage;

let logger;
let AiClassifier;
let aiRules = [];
let queue = Promise.resolve();
let queuedCount = 0;
let processing = false;

function updateActionIcon() {
    let path = "resources/img/logo32.png";
    if (processing) {
        path = "resources/img/status-classifying.png";
    } else if (queuedCount > 0) {
        path = "resources/img/status-queued.png";
    }
    if (browser.browserAction) {
        browser.browserAction.setIcon({ path });
    }
    if (browser.messageDisplayAction) {
        browser.messageDisplayAction.setIcon({ path });
    }
}

async function sha256Hex(str) {
    const buf = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(str));
    return Array.from(new Uint8Array(buf), b => b.toString(16).padStart(2, '0')).join('');
}

function byteSize(str) {
    return new TextEncoder().encode(str || "").length;
}

function replaceInlineBase64(text) {
    return text.replace(/[A-Za-z0-9+/]{100,}={0,2}/g,
        m => `[base64: ${byteSize(m)} bytes]`);
}

function collectText(part, bodyParts, attachments) {
    if (part.parts && part.parts.length) {
        for (const p of part.parts) collectText(p, bodyParts, attachments);
        return;
    }
    const ct = (part.contentType || "text/plain").toLowerCase();
    const cd = (part.headers?.["content-disposition"]?.[0] || "").toLowerCase();
    const body = String(part.body || "");
    if (cd.includes("attachment") || !ct.startsWith("text/")) {
        const nameMatch = /filename\s*=\s*"?([^";]+)/i.exec(cd) || /name\s*=\s*"?([^";]+)/i.exec(part.headers?.["content-type"]?.[0] || "");
        const name = nameMatch ? nameMatch[1] : "";
        attachments.push(`${name} (${ct}, ${part.size || byteSize(body)} bytes)`);
    } else if (ct.startsWith("text/html")) {
        const doc = new DOMParser().parseFromString(body, 'text/html');
        bodyParts.push(replaceInlineBase64(doc.body.textContent || ""));
    } else {
        bodyParts.push(replaceInlineBase64(body));
    }
}

function buildEmailText(full) {
    const bodyParts = [];
    const attachments = [];
    collectText(full, bodyParts, attachments);
    const headers = Object.entries(full.headers || {})
        .map(([k,v]) => `${k}: ${v.join(' ')}`)
        .join('\n');
    const attachInfo = `Attachments: ${attachments.length}` + (attachments.length ? "\n" + attachments.map(a => ` - ${a}`).join('\n') : "");
    return `${headers}\n${attachInfo}\n\n${bodyParts.join('\n')}`.trim();
}
async function applyAiRules(idsInput) {
    const ids = Array.isArray(idsInput) ? idsInput : [idsInput];
    if (!ids.length) return queue;

    if (!aiRules.length) {
        const { aiRules: stored } = await storage.local.get("aiRules");
        aiRules = Array.isArray(stored) ? stored.map(r => {
            if (r.actions) return r;
            const actions = [];
            if (r.tag) actions.push({ type: 'tag', tagKey: r.tag });
            if (r.moveTo) actions.push({ type: 'move', folder: r.moveTo });
            const rule = { criterion: r.criterion, actions };
            if (r.stopProcessing) rule.stopProcessing = true;
            return rule;
        }) : [];
    }

    for (const msg of ids) {
        const id = msg?.id ?? msg;
        queuedCount++;
        updateActionIcon();
        queue = queue.then(async () => {
            processing = true;
            queuedCount--;
            updateActionIcon();
            try {
                const full = await messenger.messages.getFull(id);
                const text = buildEmailText(full);

                for (const rule of aiRules) {
                    const cacheKey = await sha256Hex(`${id}|${rule.criterion}`);
                    const matched = await AiClassifier.classifyText(text, rule.criterion, cacheKey);
                    if (matched) {
                        for (const act of (rule.actions || [])) {
                            if (act.type === 'tag' && act.tagKey) {
                                await messenger.messages.update(id, { tags: [act.tagKey] });
                            } else if (act.type === 'move' && act.folder) {
                                await messenger.messages.move([id], act.folder);
                            } else if (act.type === 'junk') {
                                await messenger.messages.update(id, { junk: !!act.junk });
                            }
                        }
                        if (rule.stopProcessing) {
                            break;
                        }
                    }
                }
            } catch (e) {
                logger.aiLog("failed to apply AI rules", { level: 'error' }, e);
            } finally {
                processing = false;
                updateActionIcon();
            }
        });
    }

    return queue;
}

(async () => {
    logger = await import(browser.runtime.getURL("logger.js"));
    try {
        AiClassifier = await import(browser.runtime.getURL("modules/AiClassifier.js"));
        logger.aiLog("AiClassifier imported", {debug: true});
    } catch (e) {
        console.error("failed to import AiClassifier", e);
        return;
    }

    try {
        const store = await storage.local.get(["endpoint", "templateName", "customTemplate", "customSystemPrompt", "aiParams", "debugLogging", "aiRules"]);
        logger.setDebug(store.debugLogging);
        await AiClassifier.setConfig(store);
        aiRules = Array.isArray(store.aiRules) ? store.aiRules.map(r => {
            if (r.actions) return r;
            const actions = [];
            if (r.tag) actions.push({ type: 'tag', tagKey: r.tag });
            if (r.moveTo) actions.push({ type: 'move', folder: r.moveTo });
            const rule = { criterion: r.criterion, actions };
            if (r.stopProcessing) rule.stopProcessing = true;
            return rule;
        }) : [];
        logger.aiLog("configuration loaded", {debug: true}, store);
        storage.onChanged.addListener(async changes => {
            if (changes.aiRules) {
                const newRules = changes.aiRules.newValue || [];
                aiRules = newRules.map(r => {
                    if (r.actions) return r;
                    const actions = [];
                    if (r.tag) actions.push({ type: 'tag', tagKey: r.tag });
                    if (r.moveTo) actions.push({ type: 'move', folder: r.moveTo });
                    const rule = { criterion: r.criterion, actions };
                    if (r.stopProcessing) rule.stopProcessing = true;
                    return rule;
                });
                logger.aiLog("aiRules updated from storage change", {debug: true}, aiRules);
            }
        });
    } catch (err) {
        logger.aiLog("failed to load config", {level: 'error'}, err);
    }

    logger.aiLog("background.js loaded – ready to classify", {debug: true});

    browser.menus.create({
        id: "apply-ai-rules-list",
        title: "Apply AI Rules",
        contexts: ["message_list"],
    });
    browser.menus.create({
        id: "apply-ai-rules-display",
        title: "Apply AI Rules",
        contexts: ["message_display_action"],
    });

    if (browser.messageDisplayAction) {
        browser.messageDisplayAction.onClicked.addListener(async (tab) => {
            try {
                const msgs = await browser.messageDisplay.getDisplayedMessages(tab.id);
                const ids = msgs.map(m => m.id);
                await applyAiRules(ids);
            } catch (e) {
                logger.aiLog("failed to apply AI rules from action", { level: 'error' }, e);
            }
        });
    }

    browser.menus.onClicked.addListener(async info => {
        if (info.menuItemId === "apply-ai-rules-list" || info.menuItemId === "apply-ai-rules-display") {
            const ids = info.selectedMessages?.messages?.map(m => m.id) ||
                         (info.messageId ? [info.messageId] : []);
            await applyAiRules(ids);
        }
    });

    // Listen for messages from UI/devtools
    browser.runtime.onMessage.addListener(async (msg) => {
        logger.aiLog("onMessage received", {debug: true}, msg);

    if (msg?.type === "aiFilter:test") {
        const { text = "", criterion = "" } = msg;
        logger.aiLog("aiFilter:test – text", {debug: true}, text);
        logger.aiLog("aiFilter:test – criterion", {debug: true}, criterion);

        try {
            logger.aiLog("Calling AiClassifier.classifyText()", {debug: true});
            const result = await AiClassifier.classifyText(text, criterion);
            logger.aiLog("classify() returned", {debug: true}, result);
            return { match: result };
        }
        catch (err) {
            logger.aiLog("Error in classify()", {level: 'error'}, err);
            // rethrow so the caller sees the failure
            throw err;
        }
    }
    else {
        logger.aiLog("Unknown message type, ignoring", {level: 'warn'}, msg?.type);
    }
});

// Automatically classify new messages
if (typeof messenger !== "undefined" && messenger.messages?.onNewMailReceived) {
    messenger.messages.onNewMailReceived.addListener(async (folder, messages) => {
        logger.aiLog("onNewMailReceived", {debug: true}, messages);
        const ids = (messages?.messages || messages || []).map(m => m.id ?? m);
        await applyAiRules(ids);
    });
} else {
    logger.aiLog("messenger.messages API unavailable, skipping new mail listener", { level: 'warn' });
}

// Catch any unhandled rejections
window.addEventListener("unhandledrejection", ev => {
    logger.aiLog("Unhandled promise rejection", {level: 'error'}, ev.reason);
});

    browser.runtime.onInstalled.addListener(async ({ reason }) => {
        if (reason === "install") {
            await browser.runtime.openOptionsPage();
        }
    });

})();