package dev.ltms.bridged.herdr;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;

import static org.junit.jupiter.api.Assertions.*;

/**
 * CB-531. A lead is never spawned, so the daemon has to <em>find</em> it: these assert that an
 * operator-labelled tab is what makes a pane a lead, and — just as importantly — what does not.
 */
class LeadTabScannerTest {

    private static final ObjectMapper MAPPER = new ObjectMapper();
    private static final long TTL = TimeUnit.SECONDS.toNanos(10);

    /**
     * A herdr whose workspace/tab/pane topology is declared per test. Counts calls so the caching
     * contract can be asserted, and can be made to fail on demand.
     */
    private static final class TopologyHerdr implements HerdrClient {
        /** workspace_id → label. */
        final Map<String, String> workspaces = new LinkedHashMap<>();
        /** tab_id → [workspace_id, label]. */
        final Map<String, String[]> tabs = new LinkedHashMap<>();
        /** pane_id → [tab_id, terminal_id]. */
        final Map<String, String[]> panes = new LinkedHashMap<>();
        int calls;
        boolean failing;

        TopologyHerdr workspace(String id, String label) {
            workspaces.put(id, label);
            return this;
        }

        TopologyHerdr tab(String tabId, String workspaceId, String label) {
            tabs.put(tabId, new String[]{workspaceId, label});
            return this;
        }

        TopologyHerdr pane(String paneId, String tabId, String terminalId) {
            panes.put(paneId, new String[]{tabId, terminalId});
            return this;
        }

        @Override
        public JsonNode call(String method, Object params) {
            calls++;
            if (failing) {
                throw new HerdrException("socket closed");
            }
            List<String> items = new ArrayList<>();
            switch (method) {
                case "workspace.list" -> {
                    workspaces.forEach((id, label) -> items.add(
                            "{\"workspace_id\":\"%s\",\"label\":\"%s\"}".formatted(id, label)));
                    return read("{\"workspaces\":[%s]}".formatted(String.join(",", items)));
                }
                case "tab.list" -> {
                    String ws = String.valueOf(((Map<?, ?>) params).get("workspace_id"));
                    tabs.forEach((id, t) -> {
                        if (ws.equals(t[0])) {
                            items.add(("{\"tab_id\":\"%s\",\"workspace_id\":\"%s\",\"label\":%s,"
                                    + "\"pane_count\":1}").formatted(id, t[0],
                                    t[1] == null ? "null" : "\"" + t[1] + "\""));
                        }
                    });
                    return read("{\"tabs\":[%s]}".formatted(String.join(",", items)));
                }
                case "pane.list" -> {
                    panes.forEach((id, p) -> items.add(
                            "{\"pane_id\":\"%s\",\"tab_id\":\"%s\",\"terminal_id\":\"%s\"}"
                                    .formatted(id, p[0], p[1])));
                    return read("{\"panes\":[%s]}".formatted(String.join(",", items)));
                }
                default -> throw new AssertionError("unexpected herdr call: " + method);
            }
        }

        private static JsonNode read(String json) {
            try {
                return MAPPER.readTree(json);
            } catch (Exception e) {
                throw new AssertionError(e);
            }
        }

        @Override
        public void close() {
        }
    }

    /**
     * The usual shape: one user space with lead tabs, one worker space bridged owns.
     *
     * <p>Not closed: {@code close()} is a no-op on this fake, and every test needs the handle after
     * the scanner is built (to mutate the topology or read {@code calls}).
     */
    @SuppressWarnings("resource")
    private TopologyHerdr twoLeads() {
        return new TopologyHerdr()
                .workspace("w1", "main")
                .workspace("w9", "bridged-workers")
                .tab("w1:t1", "w1", "lead: opus-5.0")
                .tab("w1:t2", "w1", "lead: gpt-sol-5.6")
                .tab("w1:t3", "w1", "notes")
                .tab("w9:t1", "w9", "worker: gx10 #1")
                .pane("w1:p1", "w1:t1", "term_opus")
                .pane("w1:p2", "w1:t2", "term_gpt")
                .pane("w1:p3", "w1:t3", "term_notes")
                .pane("w9:p1", "w9:t1", "term_worker");
    }

    private LeadTabScanner scanner(TopologyHerdr herdr, Map<String, String> configured,
                                   AtomicLong clock) {
        return new LeadTabScanner(herdr, "lead:", Set.of("bridged-workers"), configured, TTL,
                clock::get);
    }

    @Test
    void everyLabelledTabBecomesALeadNamedByItsLabel() {
        Map<String, String> leads = scanner(twoLeads(), Map.of(), new AtomicLong()).get();

        assertEquals(Map.of("term_opus", "opus-5.0", "term_gpt", "gpt-sol-5.6"), leads,
                "two leads discovered from labels alone — no terminal_id was ever configured");
    }

    @Test
    void anUnlabelledTabContributesNothing() {
        assertFalse(scanner(twoLeads(), Map.of(), new AtomicLong()).get().containsKey("term_notes"));
    }

    /**
     * The guard that matters: bridged labels its own worker tabs, so if a worker space were scanned
     * a naming accident would promote the fleet. The exclusion is by workspace, not by hoping the
     * worker template never collides.
     */
    @Test
    void aTabInAWorkerSpaceIsNeverALeadEvenWhenItsLabelMatches() {
        TopologyHerdr herdr = twoLeads().tab("w9:t2", "w9", "lead: impostor")
                .pane("w9:p2", "w9:t2", "term_impostor");

        assertFalse(scanner(herdr, Map.of(), new AtomicLong()).get().containsKey("term_impostor"));
    }

    @Test
    void aBarePrefixNamesNobodyAndIsRejected() {
        TopologyHerdr herdr = new TopologyHerdr().workspace("w1", "main")
                .tab("w1:t1", "w1", "lead:").pane("w1:p1", "w1:t1", "term_a");

        assertEquals(Map.of(), scanner(herdr, Map.of(), new AtomicLong()).get(),
                "a lead with no name would resolve as PRIMARY with nothing to attribute it to");
    }

    @Test
    void thePrefixMatchesCaseInsensitivelyAndTheNameIsTrimmed() {
        TopologyHerdr herdr = new TopologyHerdr().workspace("w1", "main")
                .tab("w1:t1", "w1", "  LEAD:   opus-5.0  ").pane("w1:p1", "w1:t1", "term_a");

        assertEquals(Map.of("term_a", "opus-5.0"), scanner(herdr, Map.of(), new AtomicLong()).get());
    }

    @Test
    void everyPaneInALeadTabResolvesAsThatLead() {
        // A human may split their own lead tab. Both panes are theirs, so both are that lead —
        // nothing bridged placed can land here (see the worker-space test above).
        TopologyHerdr herdr = twoLeads().pane("w1:p1b", "w1:t1", "term_opus_split");

        assertEquals("opus-5.0", scanner(herdr, Map.of(), new AtomicLong()).get().get("term_opus_split"));
    }

    @Test
    void anExplicitlyConfiguredLeadIsMergedInAndOutranksALabel() {
        Map<String, String> configured = Map.of("term_opus", "pinned-name", "term_extra", "from-config");

        Map<String, String> leads = scanner(twoLeads(), configured, new AtomicLong()).get();

        assertEquals("pinned-name", leads.get("term_opus"), "an explicit pin is the operator's last word");
        assertEquals("from-config", leads.get("term_extra"), "a configured lead needs no tab at all");
        assertEquals("gpt-sol-5.6", leads.get("term_gpt"));
    }

    // ── caching ─────────────────────────────────────────────────────────────────────────────────

    @Test
    void aSecondLookupWithinTheTtlDoesNotTouchHerdr() {
        TopologyHerdr herdr = twoLeads();
        AtomicLong clock = new AtomicLong();
        LeadTabScanner s = scanner(herdr, Map.of(), clock);

        s.get();
        int afterFirst = herdr.calls;
        clock.addAndGet(TTL - 1);
        s.get();

        assertEquals(afterFirst, herdr.calls,
                "resolve() runs on every request — an un-cached scan would put herdr on that path");
    }

    @Test
    void aTabLabelledAfterStartupIsPickedUpOnceTheTtlExpires() {
        TopologyHerdr herdr = twoLeads();
        AtomicLong clock = new AtomicLong();
        LeadTabScanner s = scanner(herdr, Map.of(), clock);
        assertFalse(s.get().containsKey("term_notes"));

        herdr.tab("w1:t3", "w1", "lead: late-arrival"); // the operator renames their tab
        clock.addAndGet(TTL);

        assertEquals("late-arrival", s.get().get("term_notes"),
                "the whole point over `leaders:`: no config edit, no restart");
    }

    @Test
    void aFailedScanKeepsTheLeadsAlreadyKnownRatherThanDemotingThem() {
        TopologyHerdr herdr = twoLeads();
        AtomicLong clock = new AtomicLong();
        LeadTabScanner s = scanner(herdr, Map.of(), clock);
        Map<String, String> before = s.get();

        herdr.failing = true;
        clock.addAndGet(TTL);

        assertEquals(before, s.get(),
                "a herdr hiccup must not silently demote a live lead to a worker mid-session");
    }

    @Test
    void aFailedFirstScanStillHonoursTheConfiguredLeads() {
        TopologyHerdr herdr = twoLeads();
        herdr.failing = true;

        Map<String, String> leads = scanner(herdr, Map.of("term_x", "opus-5.0"), new AtomicLong()).get();

        assertEquals(Map.of("term_x", "opus-5.0"), leads,
                "config-named leads must not depend on herdr answering at all");
    }

    @Test
    void aDownHerdrIsRetriedOncePerTtlNotOncePerRequest() {
        TopologyHerdr herdr = twoLeads();
        herdr.failing = true;
        AtomicLong clock = new AtomicLong();
        LeadTabScanner s = scanner(herdr, Map.of(), clock);

        s.get();
        int afterFirst = herdr.calls;
        s.get();
        s.get();

        assertEquals(afterFirst, herdr.calls, "the failure path must be rate-limited too");
    }
}