/* Offline tickets: server ownership, versioned notes and polling-safe drafts. */
(function(global){
    function create(options){
        const el = id => document.getElementById(id);
        const states = {pending:"待处理", processing:"处理中", completed:"已完成"};
        let rows = [], selected = null, busy = false, loading = false;
        let generation = 0, expanded = false, hasMore = false;
        let activeQuery = "", latestSeen = null, unreadNew = 0, summaryLoading = false, overdueOnly = false;
        let historyRows = [], historyHasMore = false, historyTicketId = null, historyLoading = false, historyRequest = 0, historyError = "";
        const drafts = new Map();
        const filter = el("ticket-filter"), note = el("ticket-note");
        filter.value = "all";

        async function refreshSummary(){
            if(summaryLoading) return;
            summaryLoading = true;
            try{
                const data = await options.request("/api/tickets/summary"+(latestSeen === null ? "" : "?after="+latestSeen));
                el("ticket-pending-count").textContent = String(data.pending_count);
                const overdueCount = Number(data.overdue_count || 0);
                el("ticket-overdue-count").textContent = String(overdueCount);
                el("ticket-overdue-toggle").setAttribute("aria-label", "查看超时留言 "+overdueCount+" 条，点击筛选");
                el("ticket-section-count").textContent = "待处理 "+data.pending_count+" · 超时 "+overdueCount;
                el("ticket-inbox-toggle").setAttribute("aria-label", "待处理留言 "+data.pending_count+" 条，点击查看");
                el("ticket-summary-status").textContent = "";
                if(latestSeen !== null && data.latest_id > latestSeen && data.new_count > 0){
                    unreadNew += data.new_count;
                    el("ticket-alert-text").textContent = "收到 "+unreadNew+" 条新留言";
                    el("ticket-alert").hidden = false;
                    if(options.notify) options.notify("新离线留言", "有 "+data.new_count+" 条新留言，请进入后台查看。");
                }
                latestSeen = Math.max(latestSeen || 0, data.latest_id);
            }catch(error){
                el("ticket-summary-status").textContent = "待处理数量暂时无法更新，稍后自动重试。";
            }finally{ summaryLoading = false; }
        }

        function message(text, failed){
            el("ticket-status-message").textContent = text || "";
            el("ticket-status-message").classList.toggle("is-error", Boolean(failed));
        }

        const eventLabels = {submitted:"提交留言", claimed:"领取留言", note_updated:"修改备注", completed:"标记完成", legacy_snapshot:"升级时保留状态"};
        function eventDetail(event){
            if(event.action === "note_updated") return "旧备注："+(event.old_note || "（空）")+"\n新备注："+(event.new_note || "（空）");
            if(event.action === "completed") return event.new_note ? "处理结果："+event.new_note : "";
            if(event.action === "legacy_snapshot") return "升级前的处理过程未记录，仅保留当时已知状态。";
            return "";
        }
        function renderHistory(){
            const list = el("ticket-history-list"), status = el("ticket-history-status");
            el("ticket-history-more").hidden = !historyHasMore;
            el("ticket-history-more").disabled = historyLoading;
            if(historyLoading && !historyRows.length){ status.textContent = "正在加载处理记录…"; list.innerHTML = ""; return; }
            if(!historyRows.length){ status.textContent = historyError || "暂无处理记录。"; list.innerHTML = ""; return; }
            status.textContent = historyError;
            list.innerHTML = historyRows.map(function(event){
                const detail = eventDetail(event);
                return '<li class="ticket-history-item"><span class="ticket-history-action">'+options.escape(eventLabels[event.action] || event.action)+'</span> · '+options.escape(event.actor_name || "系统")+'<span class="ticket-history-meta"> · '+options.escape(event.ctime || "")+'</span>'+
                    (detail ? '<span class="ticket-history-detail">'+options.escape(detail)+'</span>' : '')+'</li>';
            }).join("");
        }
        async function loadHistory(reset){
            if(!selected) return;
            const id = selected.id, request = ++historyRequest;
            if(reset || historyTicketId !== id){ historyRows = []; historyHasMore = false; historyTicketId = id; }
            historyLoading = true; historyError = ""; renderHistory();
            const before = !reset && historyRows.length ? "&before="+historyRows[historyRows.length-1].id : "";
            try{
                const data = await options.request("/api/tickets/"+id+"/events?limit=20"+before);
                if(request !== historyRequest || !selected || selected.id !== id) return;
                const list = Array.isArray(data) ? data : [];
                historyRows = reset ? list : historyRows.concat(list.filter(function(item){ return !historyRows.some(function(row){ return row.id === item.id; }); }));
                historyHasMore = list.length === 20;
                el("ticket-history-status").textContent = "";
            }catch(error){
                if(request === historyRequest) historyError = "处理记录加载失败，请点击刷新记录重试。";
            }finally{
                if(request === historyRequest){ historyLoading = false; renderHistory(); }
            }
        }

        function renderDetail(){
            el("ticket-selected").hidden = !selected;
            if(!selected) return;
            const mine = selected.status === "processing" && selected.owner_username === options.username;
            const draft = drafts.get(selected.id);
            const conflict = Boolean(draft && draft.version !== selected.version);
            el("ticket-content").textContent = selected.content;
            el("ticket-meta").textContent = "#"+selected.id+" · "+selected.ctime+" · 电话："+(selected.phone || "未提供");
            el("ticket-owner").textContent = "负责人："+(selected.owner_name || selected.owner_username || "未领取")+
                (selected.owner_username === options.username ? "（我）" : "");
            const overdue = el("ticket-overdue-hint");
            if(selected.overdue_kind){
                overdue.hidden = false;
                overdue.textContent = (selected.overdue_kind === "pending" ? "尚未领取，已超时 " : "领取后处理已超时 ")+selected.overdue_minutes+" 分钟。";
            }else if(selected.status === "processing" && !selected.claimed_at){
                overdue.hidden = false;
                overdue.textContent = "缺少领取时间，无法计算处理超时。";
            }else{ overdue.hidden = true; overdue.textContent = ""; }
            if(selected.status === "processing" && selected.claimed_at_estimated){
                overdue.hidden = false;
                overdue.textContent += " 旧留言按升级前最后更新时间估算领取时间。";
            }
            el("ticket-state").textContent = states[selected.status] || selected.status;
            el("ticket-state").setAttribute("data-state", selected.status);
            note.value = draft ? draft.text : (selected.note || "");
            note.readOnly = !mine || busy;
            el("ticket-claim").hidden = selected.status !== "pending";
            el("ticket-save").hidden = !mine;
            el("ticket-complete").hidden = !mine;
            ["ticket-claim", "ticket-save", "ticket-complete"].forEach(id => {
                el(id).disabled = busy || (id !== "ticket-claim" && conflict);
            });
            el("ticket-server-note").hidden = !conflict;
            el("ticket-server-note").textContent = conflict ? "这条留言已更新，当前保存的备注："+(selected.note || "（空）") : "";
            el("ticket-rebase").hidden = !conflict || !mine;
            el("ticket-rebase").disabled = busy;
            el("ticket-activity").textContent = selected.completed_at ? "完成时间："+selected.completed_at :
                (selected.updated_at ? "更新时间："+selected.updated_at : "");
            renderHistory();
        }

        function render(){
            el("ticketList").innerHTML = rows.length ? rows.map(ticket =>
                '<button type="button" class="ticket-item" data-ticket-id="'+ticket.id+'" aria-pressed="'+Boolean(selected && ticket.id === selected.id)+'"'+(busy ? ' disabled' : '')+'>'+
                '<span class="ticket-summary">'+options.escape(ticket.content)+'</span><span class="ticket-row"><span><span class="ticket-state" data-state="'+options.escape(ticket.status)+'">'+options.escape(states[ticket.status] || ticket.status)+'</span>'+(ticket.overdue_kind ? '<span class="ticket-overdue-badge">'+options.escape(ticket.overdue_kind === "pending" ? "领取超时 "+ticket.overdue_minutes+" 分钟" : "处理超时 "+ticket.overdue_minutes+" 分钟")+'</span>' : '')+'</span><span>'+options.escape(ticket.owner_name || ticket.owner_username || "未领取")+'</span></span>'+ 
                '<span class="ticket-time">'+options.escape(ticket.ctime)+'</span></button>'
            ).join("") : '<p class="ticket-empty">'+(activeQuery ? "没有匹配的留言，请更换关键词或状态" : "该状态下暂无留言")+'</p>';
            el("ticket-more").hidden = !hasMore;
            el("ticket-more").disabled = loading || busy;
            el("ticket-refresh").disabled = loading || busy;
            filter.disabled = busy;
            el("ticket-search").disabled = busy;
            el("ticket-search-submit").disabled = busy;
            el("ticket-search-clear").hidden = !activeQuery;
            el("ticket-search-clear").disabled = busy;
            el("ticket-overdue-filter").disabled = busy;
            renderDetail();
        }

        async function load(more, manual){
            if(busy || (loading && !manual) || (expanded && !more && !manual)) return;
            const current = ++generation;
            loading = true;
            el("ticket-refresh").disabled = true;
            el("ticket-more").disabled = true;
            const before = more && rows.length ? "&before="+rows[rows.length-1].id : "";
            const previousId = selected && selected.id, previousVersion = selected && selected.version;
            try{
                const list = await options.request("/api/tickets?status="+filter.value+"&limit=20"+before+
                    (activeQuery ? "&q="+encodeURIComponent(activeQuery) : "")+(overdueOnly ? "&overdue=1" : ""));
                if(current !== generation) return;
                rows = more ? rows.concat(list.filter(item => !rows.some(row => row.id === item.id))) : list;
                hasMore = list.length === 20;
                expanded = Boolean(more);
                if(selected){
                    const found = rows.find(item => item.id === selected.id);
                    if(found) selected = found;
                    else{
                        const id = selected.id;
                        const data = await options.request("/api/tickets/"+id);
                        if(current !== generation) return;
                        if(selected && selected.id === id) selected = data.ticket;
                    }
                }else if(rows.length){ selected = rows[0]; }
                if(current === generation){
                    render();
                    if(selected && (selected.id !== previousId || selected.version !== previousVersion || historyTicketId !== selected.id)) loadHistory(true);
                }
            }catch(error){
                if(current === generation) message("留言加载失败，请点击刷新重试；未保存的备注仍保留。", true);
            }finally{
                if(current === generation){ loading = false; render(); }
            }
        }

        function select(id){
            if(busy) return;
            const ticket = rows.find(row => row.id === Number(id));
            if(!ticket) return;
            selected = ticket;
            message("");
            render();
            loadHistory(true);
        }

        async function update(action){
            if(busy || !selected) return;
            const ticket = selected;
            const draft = drafts.get(ticket.id);
            if(action !== "claim" && (ticket.status !== "processing" || ticket.owner_username !== options.username)) return;
            if(action !== "claim" && draft && draft.version !== ticket.version){
                message("留言已更新，请核对当前保存的备注后再处理。", true); return;
            }
            const text = note.value;
            if(action === "completed" && !text.trim()){
                message("请先填写处理结果，再标记完成。", true); note.focus(); return;
            }
            if(action !== "claim") drafts.set(ticket.id, {text:text, version:draft ? draft.version : ticket.version});
            ++generation;
            loading = false;
            busy = true;
            render();
            message(action === "claim" ? "正在领取…" : "正在保存…");
            try{
                const result = await options.request("/api/tickets/"+ticket.id+(action === "claim" ? "/claim" : ""), {
                    method: action === "claim" ? "POST" : "PATCH", headers:{"Content-Type":"application/json"},
                    body:JSON.stringify(action === "claim" ? {} : {version:draft ? draft.version : ticket.version,
                        note:text, status:action === "completed" ? "completed" : "processing"})
                });
                selected = result.ticket;
                rows = rows.map(row => row.id === ticket.id ? result.ticket : row);
                drafts.delete(ticket.id);
                message(action === "claim" ? "已领取，由你负责跟进。" : action === "completed" ? "已完成，记录已保留。" : "备注已保存。");
            }catch(error){
                message(error.userMessage || "操作未确认成功，请刷新核对后重试；备注已保留。", true);
                if(error.status === 409 || error.status === 403){
                    try{
                        const data = await options.request("/api/tickets/"+ticket.id);
                        selected = data.ticket;
                        rows = rows.map(row => row.id === ticket.id ? selected : row);
                    }catch(refreshError){ /* Keep the local draft and error until explicit retry. */ }
                }
            }finally{ busy = false; render(); loadHistory(true); await refreshSummary(); }
        }

        function search(){
            if(busy) return;
            const query = el("ticket-search").value.trim();
            if(query.length > 100){ message("搜索关键词最多 100 字。", true); return; }
            activeQuery = query;
            selected = null; rows = []; expanded = false; hasMore = false;
            message(""); render();
            return load(false, true);
        }

        function viewPending(){
            if(busy){ message("正在保存，请稍后查看新留言。"); return; }
            unreadNew = 0;
            el("ticket-alert").hidden = true;
            filter.value = "pending";
            overdueOnly = false; el("ticket-overdue-filter").checked = false;
            el("ticket-search").value = "";
            if(options.open) options.open();
            return search();
        }

        note.addEventListener("input", function(){
            if(!selected || note.readOnly) return;
            const previous = drafts.get(selected.id);
            drafts.set(selected.id, {text:note.value, version:previous ? previous.version : selected.version});
        });
        el("ticketList").addEventListener("click", function(event){
            const button = event.target.closest("[data-ticket-id]");
            if(button) select(button.getAttribute("data-ticket-id"));
        });
        filter.addEventListener("change", function(){ selected = null; rows = []; expanded = false; message(""); render(); load(false, true); });
        el("ticket-search-form").addEventListener("submit", function(event){ event.preventDefault(); return search(); });
        el("ticket-search").addEventListener("keydown", function(event){
            if(event.key === "Enter" && event.isComposing) event.preventDefault();
        });
        el("ticket-search-clear").onclick = function(){ el("ticket-search").value = ""; return search(); };
        el("ticket-inbox-toggle").onclick = viewPending;
        el("ticket-alert-view").onclick = viewPending;
        el("ticket-overdue-toggle").onclick = function(){
            if(busy) return;
            filter.value = "all"; overdueOnly = true; el("ticket-overdue-filter").checked = true;
            el("ticket-search").value = "";
            if(options.open) options.open("ticket-overdue-toggle");
            return search();
        };
        el("ticket-overdue-filter").addEventListener("change", function(){
            overdueOnly = Boolean(this.checked); selected = null; rows = []; expanded = false;
            return load(false, true);
        });
        el("ticket-history-reload").onclick = function(){ return loadHistory(true); };
        el("ticket-history-more").onclick = function(){ if(!historyLoading && historyHasMore) return loadHistory(false); };
        el("ticket-refresh").onclick = function(){ return load(false, true); };
        el("ticket-more").onclick = function(){ return load(true); };
        el("ticket-claim").onclick = function(){ return update("claim"); };
        el("ticket-save").onclick = function(){ return update("save"); };
        el("ticket-complete").onclick = function(){ return update("completed"); };
        el("ticket-rebase").onclick = function(){
            if(!selected || busy) return;
            const draft = drafts.get(selected.id);
            if(draft){ draft.version = selected.version; render(); message("已保留你的草稿，请确认内容后保存。"); }
        };
        return {load:load, select:select, refreshSummary:refreshSummary};
    }
    global.AdminTickets = {create:create};
})(window);