import * as Clipboard from "expo-clipboard";
import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import {
  Platform,
  Pressable,
  ScrollView,
  Text,
  View,
  type PressableStateCallbackType,
} from "react-native";
import { Copy, RotateCw } from "lucide-react-native";
import { StyleSheet, withUnistyles } from "react-native-unistyles";
import { useTranslation } from "react-i18next";

import { AdaptiveModalSheet, type SheetHeader } from "@/components/adaptive-modal-sheet";
import { LoadingSpinner } from "@/components/ui/loading-spinner";
import { useToast } from "@/contexts/toast-context";
import { getDesktopDaemonLogs, getDesktopDaemonStatus } from "@/desktop/daemon/desktop-daemon";
import {
  formatAppDiagnosticHeader,
  formatDiagnosticSection,
  formatHostRuntimeSection,
  formatServerInfoSection,
  redactAppDiagnosticReport,
} from "@/diagnostics/app-diagnostic-report";
import { getHostRuntimeStore, useHosts, type HostRuntimeSnapshot } from "@/runtime/host-runtime";
import { settingsStyles } from "@/styles/settings";
import { ICON_SIZE, type Theme } from "@/styles/theme";
import type { HostProfile } from "@/types/host-connection";

interface AppDiagnosticSheetProps {
  visible: boolean;
  onClose: () => void;
  appVersion: string | null;
  isDesktopApp: boolean;
}

type ProgressStatus = "pending" | "running" | "done" | "failed";

interface ProgressRow {
  id: string;
  label: string;
  status: ProgressStatus;
}

interface DiagnosticCollectionResult {
  sections: string[];
  status: ProgressStatus;
}

const SNAP_POINTS = ["55%", "88%"];
const ThemedCopy = withUnistyles(Copy);
const ThemedRotateCw = withUnistyles(RotateCw);
const ThemedLoadingSpinner = withUnistyles(LoadingSpinner);
const foregroundMutedColorMapping = (theme: Theme) => ({
  color: theme.colors.foregroundMuted,
});

export function AppDiagnosticSheet({
  visible,
  onClose,
  appVersion,
  isDesktopApp,
}: AppDiagnosticSheetProps) {
  const { t } = useTranslation();
  const toast = useToast();
  const hosts = useHosts();
  const [diagnostic, setDiagnostic] = useState<string | null>(null);
  const [loading, setLoading] = useState(false);
  const [progress, setProgress] = useState<ProgressRow[]>([]);
  const runIdRef = useRef(0);

  const updateProgress = useCallback((id: string, label: string, status: ProgressStatus) => {
    setProgress((current) => {
      const existing = current.find((row) => row.id === id);
      if (existing) {
        return current.map((row) => (row.id === id ? { ...row, label, status } : row));
      }
      return [...current, { id, label, status }];
    });
  }, []);

  const runDiagnostics = useCallback(async () => {
    const runId = runIdRef.current + 1;
    runIdRef.current = runId;
    const isCurrentRun = () => runIdRef.current === runId;
    const updateRunProgress = (id: string, label: string, status: ProgressStatus) => {
      if (isCurrentRun()) {
        updateProgress(id, label, status);
      }
    };

    setLoading(true);
    setDiagnostic(null);
    setProgress([]);

    const sections: string[] = [];
    try {
      updateRunProgress("client", t("settings.diagnostics.app.progress.client"), "running");
      sections.push(
        formatAppDiagnosticHeader({
          appVersion,
          platform: Platform.OS,
          isDesktopApp,
          hostCount: hosts.length,
        }),
      );
      updateRunProgress("client", t("settings.diagnostics.app.progress.client"), "done");

      if (isDesktopApp) {
        const desktopLabel = t("settings.diagnostics.app.progress.desktop");
        updateRunProgress("desktop", desktopLabel, "running");
        const desktopResult = await collectDesktopDiagnosticSections();
        sections.push(...desktopResult.sections);
        updateRunProgress("desktop", desktopLabel, desktopResult.status);
      }

      const store = getHostRuntimeStore();
      for (const host of hosts) {
        const hostProgressId = `host:${host.serverId}`;
        updateRunProgress(hostProgressId, host.label, "running");
        const snapshot = store.getSnapshot(host.serverId);
        const hostResult = await collectHostDiagnosticSections(host, snapshot);
        sections.push(...hostResult.sections);
        updateRunProgress(hostProgressId, host.label, hostResult.status);
      }

      if (isCurrentRun()) {
        setDiagnostic(redactAppDiagnosticReport(sections.join("\n\n"), hosts));
      }
    } finally {
      if (isCurrentRun()) {
        setLoading(false);
      }
    }
  }, [appVersion, hosts, isDesktopApp, t, updateProgress]);

  useEffect(() => {
    if (visible) {
      void runDiagnostics();
    } else {
      runIdRef.current += 1;
      setLoading(false);
      setDiagnostic(null);
      setProgress([]);
    }
  }, [visible, runDiagnostics]);

  const handleRefreshPress = useCallback(() => {
    void runDiagnostics();
  }, [runDiagnostics]);

  const handleCopyPress = useCallback(() => {
    if (!diagnostic) return;
    void Clipboard.setStringAsync(diagnostic)
      .then(() => toast.copied(t("settings.diagnostics.app.copyLabel")))
      .catch(() => toast.error(t("settings.diagnostics.app.copyFailed")));
  }, [diagnostic, t, toast]);

  const iconButtonStyle = useCallback(
    ({ hovered, pressed }: PressableStateCallbackType & { hovered?: boolean }) => [
      styles.iconButton,
      (Boolean(hovered) || pressed) && styles.iconButtonHovered,
    ],
    [],
  );

  const disabledIconButtonStyle = useCallback(
    ({ hovered, pressed }: PressableStateCallbackType & { hovered?: boolean }) => [
      styles.iconButton,
      (Boolean(hovered) || pressed) && Boolean(diagnostic) && styles.iconButtonHovered,
      diagnostic ? null : styles.disabled,
    ],
    [diagnostic],
  );

  const header = useMemo<SheetHeader>(
    () => ({
      title: t("settings.diagnostics.app.title"),
      actions: (
        <View style={styles.headerActions}>
          <Pressable
            onPress={handleCopyPress}
            disabled={!diagnostic}
            hitSlop={8}
            style={disabledIconButtonStyle}
            accessibilityRole="button"
            accessibilityLabel={t("settings.diagnostics.app.copyAccessibility")}
          >
            <ThemedCopy size={ICON_SIZE.sm} uniProps={foregroundMutedColorMapping} />
          </Pressable>
          <Pressable
            onPress={handleRefreshPress}
            disabled={loading}
            hitSlop={8}
            style={iconButtonStyle}
            accessibilityRole="button"
            accessibilityLabel={
              loading
                ? t("settings.diagnostics.app.refreshingAccessibility")
                : t("settings.diagnostics.app.refreshAccessibility")
            }
          >
            {loading ? (
              <ThemedLoadingSpinner size={ICON_SIZE.sm} uniProps={foregroundMutedColorMapping} />
            ) : (
              <ThemedRotateCw size={ICON_SIZE.sm} uniProps={foregroundMutedColorMapping} />
            )}
          </Pressable>
        </View>
      ),
    }),
    [
      diagnostic,
      disabledIconButtonStyle,
      handleCopyPress,
      handleRefreshPress,
      iconButtonStyle,
      loading,
      t,
    ],
  );

  return (
    <AdaptiveModalSheet
      header={header}
      visible={visible}
      onClose={onClose}
      snapPoints={SNAP_POINTS}
      scrollable={false}
      testID="app-diagnostic-sheet"
    >
      <View style={DIAGNOSTIC_CARD_STYLE}>
        {diagnostic ? (
          <ScrollView style={styles.codeScroll} contentContainerStyle={styles.codeContent}>
            <ScrollView horizontal showsHorizontalScrollIndicator>
              <Text style={styles.codeText} selectable>
                {diagnostic}
              </Text>
            </ScrollView>
          </ScrollView>
        ) : (
          <View style={styles.progressContent}>
            {progress.length === 0 ? (
              <View style={styles.progressRow}>
                <ThemedLoadingSpinner size={ICON_SIZE.sm} uniProps={foregroundMutedColorMapping} />
                <Text style={styles.mutedText}>{t("settings.diagnostics.app.running")}</Text>
              </View>
            ) : (
              progress.map((row) => (
                <View key={row.id} style={styles.progressRow}>
                  {row.status === "running" || row.status === "pending" ? (
                    <ThemedLoadingSpinner
                      size={ICON_SIZE.sm}
                      uniProps={foregroundMutedColorMapping}
                    />
                  ) : (
                    <View
                      style={row.status === "failed" ? FAILED_STATUS_DOT_STYLE : styles.statusDot}
                    />
                  )}
                  <Text
                    style={styles.mutedText}
                  >{`${row.label}: ${formatProgressStatus(row.status)}`}</Text>
                </View>
              ))
            )}
          </View>
        )}
      </View>
    </AdaptiveModalSheet>
  );
}

async function collectDesktopDiagnosticSections(): Promise<DiagnosticCollectionResult> {
  try {
    const [status, logs] = await Promise.all([getDesktopDaemonStatus(), getDesktopDaemonLogs()]);
    return {
      status: "done",
      sections: [
        formatDiagnosticSection("Desktop", [
          { label: "Daemon status", value: status.status },
          { label: "Desktop managed", value: String(status.desktopManaged) },
          { label: "Daemon PID", value: status.pid === null ? "none" : String(status.pid) },
          { label: "Daemon version", value: status.version ?? "unknown" },
          { label: "Daemon home", value: status.home || "unknown" },
          { label: "Log path", value: logs.logPath || "unknown" },
          { label: "Error", value: status.error ?? "none" },
        ]),
        [
          "Desktop daemon log tail",
          logs.contents ? indentBlock(logs.contents) : "  No log lines found",
        ].join("\n"),
      ],
    };
  } catch (error) {
    return {
      status: "failed",
      sections: [formatDiagnosticSection("Desktop", [{ label: "Error", value: toMessage(error) }])],
    };
  }
}

async function collectHostDiagnosticSections(
  host: HostProfile,
  snapshot: HostRuntimeSnapshot | null,
): Promise<DiagnosticCollectionResult> {
  const sections = [formatHostRuntimeSection({ host, snapshot })];
  const client = snapshot?.client ?? null;
  if (snapshot?.connectionStatus !== "online" || !client) {
    sections.push(
      formatDiagnosticSection(`Host diagnostics: ${host.label}`, [
        { label: "Status", value: "host is not connected" },
      ]),
    );
    return { sections, status: "done" };
  }

  try {
    const serverInfo = client.getLastServerInfoMessage();
    sections.push(formatServerInfoSection(serverInfo));

    const rttMs = await client.measureLatency({ timeoutMs: 5000 });
    sections.push(
      formatDiagnosticSection(`Host latency: ${host.label}`, [
        { label: "Active RTT", value: `${Math.round(rttMs)}ms` },
      ]),
    );

    if (serverInfo?.features?.daemonDiagnostics === true) {
      const result = await client.collectDiagnostics();
      sections.push(result.diagnostic);
    } else {
      sections.push(
        formatDiagnosticSection(`Daemon diagnostics: ${host.label}`, [
          { label: "Status", value: "unsupported by this daemon" },
        ]),
      );
    }

    return { sections, status: "done" };
  } catch (error) {
    sections.push(
      formatDiagnosticSection(`Host diagnostics: ${host.label}`, [
        { label: "Error", value: toMessage(error) },
      ]),
    );
    return { sections, status: "failed" };
  }
}

function indentBlock(value: string): string {
  return value
    .split("\n")
    .filter(Boolean)
    .map((line) => `  ${line}`)
    .join("\n");
}

function toMessage(error: unknown): string {
  return error instanceof Error ? error.message : String(error);
}

function formatProgressStatus(status: ProgressStatus): string {
  switch (status) {
    case "done":
      return "done";
    case "failed":
      return "failed";
    case "running":
    case "pending":
      return "running";
  }
}

const styles = StyleSheet.create((theme) => ({
  diagnosticCard: {
    overflow: "hidden",
  },
  codeScroll: {
    maxHeight: 520,
  },
  codeContent: {
    paddingVertical: theme.spacing[3],
    paddingHorizontal: theme.spacing[4],
  },
  codeText: {
    fontFamily: theme.fontFamily.mono,
    fontSize: theme.fontSize.code,
    color: theme.colors.foreground,
    lineHeight: 18,
  },
  progressContent: {
    paddingVertical: theme.spacing[4],
    paddingHorizontal: theme.spacing[4],
    gap: theme.spacing[3],
  },
  progressRow: {
    flexDirection: "row",
    alignItems: "center",
    gap: theme.spacing[2],
    minHeight: 24,
  },
  mutedText: {
    flex: 1,
    fontSize: theme.fontSize.sm,
    color: theme.colors.foregroundMuted,
  },
  headerActions: {
    flexDirection: "row",
    alignItems: "center",
    gap: theme.spacing[1],
  },
  iconButton: {
    width: 28,
    height: 28,
    borderRadius: theme.borderRadius.full,
    alignItems: "center",
    justifyContent: "center",
  },
  iconButtonHovered: {
    backgroundColor: theme.colors.surface2,
  },
  disabled: {
    opacity: 0.5,
  },
  statusDot: {
    width: 8,
    height: 8,
    borderRadius: theme.borderRadius.full,
    backgroundColor: theme.colors.success,
  },
  statusDotFailed: {
    backgroundColor: theme.colors.destructive,
  },
}));

const DIAGNOSTIC_CARD_STYLE = [settingsStyles.card, styles.diagnosticCard];
const FAILED_STATUS_DOT_STYLE = [styles.statusDot, styles.statusDotFailed];