"use client";

import { useCallback, useEffect, useState } from "react";
import { IconHexagon } from "@tabler/icons-react";
import { Button } from "@kandev/ui/button";
import { Card, CardContent } from "@kandev/ui/card";
import { Input } from "@kandev/ui/input";
import { Label } from "@kandev/ui/label";
import { Separator } from "@kandev/ui/separator";
import { Alert, AlertDescription } from "@kandev/ui/alert";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@kandev/ui/select";
import { Switch } from "@kandev/ui/switch";
import { useToast } from "@/components/toast-provider";
import { SettingsSection } from "@/components/settings/settings-section";
import { useLinearEnabled } from "@/hooks/domains/linear/use-linear-enabled";
import {
  IntegrationAuthStatusBanner,
  type IntegrationAuthHealth,
} from "@/components/integrations/auth-status-banner";
import { INTEGRATION_STATUS_REFRESH_MS } from "@/hooks/domains/integrations/use-integration-availability";
import {
  getLinearConfig,
  setLinearConfig,
  deleteLinearConfig,
  testLinearConnection,
  listLinearTeams,
} from "@/lib/api/domains/linear-api";
import type { LinearConfig, LinearTeam, TestLinearConnectionResult } from "@/lib/types/linear";
import { LinearIssueWatchersSection } from "./linear-issue-watchers-section";

type FormState = {
  defaultTeamKey: string;
  secret: string;
};

const emptyForm: FormState = { defaultTeamKey: "", secret: "" };

function configToForm(cfg: LinearConfig | null): FormState {
  if (!cfg) return emptyForm;
  return { defaultTeamKey: cfg.defaultTeamKey, secret: "" };
}

function saveLabel(saving: boolean, hasConfig: boolean): string {
  if (saving) return "Saving...";
  return hasConfig ? "Update" : "Save";
}

type FieldsRowProps = {
  form: FormState;
  loading: boolean;
  update: <K extends keyof FormState>(key: K, value: FormState[K]) => void;
  hasSavedSecret: boolean;
  teams: LinearTeam[];
  loadingTeams: boolean;
};

function SecretField({
  form,
  loading,
  update,
  hasSavedSecret,
}: Omit<FieldsRowProps, "teams" | "loadingTeams">) {
  return (
    <div className="space-y-1.5">
      <Label htmlFor="linear-secret">
        API key
        {hasSavedSecret && (
          <span className="text-xs text-muted-foreground ml-2">
            (saved — leave blank to keep the current value)
          </span>
        )}
      </Label>
      <Input
        id="linear-secret"
        data-testid="linear-secret-input"
        type="password"
        placeholder={hasSavedSecret ? "••••••••" : "lin_api_..."}
        value={form.secret}
        onChange={(e) => update("secret", e.target.value)}
        disabled={loading}
      />
      <p className="text-xs text-muted-foreground">
        Create a personal API key at{" "}
        <a
          className="underline cursor-pointer"
          href="https://linear.app/settings/account/security"
          target="_blank"
          rel="noreferrer"
        >
          linear.app/settings/account/security
        </a>
      </p>
    </div>
  );
}

function TeamSelector({ form, loading, update, teams, loadingTeams }: FieldsRowProps) {
  return (
    <div className="space-y-1.5">
      <Label htmlFor="linear-team">Default team (optional)</Label>
      <Select
        value={form.defaultTeamKey || "__none__"}
        onValueChange={(v) => update("defaultTeamKey", v === "__none__" ? "" : v)}
        disabled={loading || loadingTeams}
      >
        <SelectTrigger id="linear-team" className="w-full">
          <SelectValue placeholder={loadingTeams ? "Loading teams…" : "Choose a team"} />
        </SelectTrigger>
        <SelectContent>
          <SelectItem value="__none__">No default</SelectItem>
          {teams.map((t) => (
            <SelectItem key={t.id} value={t.key}>
              {t.name} ({t.key})
            </SelectItem>
          ))}
        </SelectContent>
      </Select>
    </div>
  );
}

function TestResultAlert({ result }: { result: TestLinearConnectionResult | null }) {
  if (!result) return null;
  return (
    <Alert variant={result.ok ? "default" : "destructive"}>
      <AlertDescription>
        {result.ok
          ? `Connected as ${result.displayName || result.email || result.userId}${result.orgName ? ` (${result.orgName})` : ""}`
          : `Failed: ${result.error}`}
      </AlertDescription>
    </Alert>
  );
}

function configToHealth(config: LinearConfig | null): IntegrationAuthHealth | null {
  if (!config?.hasSecret) return null;
  if (!config.lastCheckedAt) return { ok: false, error: "", checkedAt: null };
  return {
    ok: !!config.lastOk,
    error: config.lastError ?? "",
    checkedAt: new Date(config.lastCheckedAt),
  };
}

type ActionBarProps = {
  saving: boolean;
  testing: boolean;
  loading: boolean;
  hasConfig: boolean;
  disableSave: boolean;
  disableTest: boolean;
  onTest: () => void;
  onSave: () => void;
  onDelete: () => void;
};

function ActionBar({
  saving,
  testing,
  loading,
  hasConfig,
  disableSave,
  disableTest,
  onTest,
  onSave,
  onDelete,
}: ActionBarProps) {
  return (
    <div className="flex flex-wrap items-center gap-2">
      <Button
        type="button"
        variant="outline"
        onClick={onTest}
        disabled={testing || loading || disableTest}
        className="cursor-pointer"
        title={disableTest ? "Paste an API key to test the connection" : undefined}
        data-testid="linear-test-button"
      >
        {testing ? "Testing..." : "Test connection"}
      </Button>
      <Button
        type="button"
        onClick={onSave}
        disabled={disableSave}
        className="cursor-pointer"
        data-testid="linear-save-button"
      >
        {saveLabel(saving, hasConfig)}
      </Button>
      {hasConfig && (
        <Button
          type="button"
          variant="destructive"
          onClick={onDelete}
          className="ml-auto cursor-pointer"
          data-testid="linear-delete-button"
        >
          Remove configuration
        </Button>
      )}
    </div>
  );
}

type SettingsActionsArgs = {
  form: FormState;
  setConfig: (cfg: LinearConfig | null) => void;
  setForm: (form: FormState) => void;
  setTestResult: (r: TestLinearConnectionResult | null) => void;
};

function useSettingsActions({ form, setConfig, setForm, setTestResult }: SettingsActionsArgs) {
  const { toast } = useToast();
  const [saving, setSaving] = useState(false);
  const [testing, setTesting] = useState(false);

  const handleTest = useCallback(async () => {
    setTesting(true);
    setTestResult(null);
    try {
      const res = await testLinearConnection({
        authMethod: "api_key",
        secret: form.secret || undefined,
      });
      setTestResult(res);
    } catch (err) {
      setTestResult({ ok: false, error: String(err) });
    } finally {
      setTesting(false);
    }
  }, [form, setTestResult]);

  const handleSave = useCallback(async () => {
    setSaving(true);
    try {
      const saved = await setLinearConfig({
        authMethod: "api_key",
        defaultTeamKey: form.defaultTeamKey,
        secret: form.secret || undefined,
      });
      setConfig(saved);
      setForm(configToForm(saved));
      setTestResult(null);
      toast({ description: "Linear configuration saved", variant: "success" });
    } catch (err) {
      toast({ description: `Save failed: ${String(err)}`, variant: "error" });
    } finally {
      setSaving(false);
    }
  }, [form, toast, setConfig, setForm, setTestResult]);

  const handleDelete = useCallback(async () => {
    if (!confirm("Remove Linear configuration?")) return;
    try {
      await deleteLinearConfig();
      setConfig(null);
      setForm(emptyForm);
      setTestResult(null);
      toast({ description: "Linear configuration removed", variant: "success" });
    } catch (err) {
      toast({ description: `Delete failed: ${String(err)}`, variant: "error" });
    }
  }, [toast, setConfig, setForm, setTestResult]);

  return { saving, testing, handleTest, handleSave, handleDelete };
}

function useTeamsLoader(hasSecret: boolean | undefined, lastOk: boolean | undefined) {
  // `teams === null` means "no fetch attempt yet", so the dropdown can show a
  // "Loading…" placeholder without us calling setState synchronously inside
  // the effect (which the lint rule forbids). Once a fetch settles we always
  // store an array, even if empty.
  const [teams, setTeams] = useState<LinearTeam[] | null>(null);
  // Fetch teams once a working configuration exists. Skips when there's no
  // saved secret (the API call would 503). Stale teams from a previous save
  // remain visible after deletion, but the dropdown is gated on hasSecret so
  // the user never sees them.
  useEffect(() => {
    if (!hasSecret) return;
    let cancelled = false;
    listLinearTeams()
      .then((res) => {
        if (!cancelled) setTeams(res.teams ?? []);
      })
      .catch(() => {
        if (!cancelled) setTeams([]);
      });
    return () => {
      cancelled = true;
    };
  }, [hasSecret, lastOk]);
  return { teams: teams ?? [], loadingTeams: teams === null && !!hasSecret };
}

function useLinearSettings() {
  const { toast } = useToast();
  const [config, setConfig] = useState<LinearConfig | null>(null);
  const [form, setForm] = useState<FormState>(emptyForm);
  const [loading, setLoading] = useState(true);
  const [testResult, setTestResult] = useState<TestLinearConnectionResult | null>(null);
  const health = configToHealth(config);
  const { teams, loadingTeams } = useTeamsLoader(config?.hasSecret, config?.lastOk);

  const load = useCallback(async () => {
    setLoading(true);
    try {
      const cfg = await getLinearConfig();
      setConfig(cfg);
      setForm(configToForm(cfg));
    } catch (err) {
      toast({ description: `Failed to load Linear config: ${String(err)}`, variant: "error" });
    } finally {
      setLoading(false);
    }
  }, [toast]);

  useEffect(() => {
    void load();
  }, [load]);

  // Background refresh so the auth-health banner picks up new probe results.
  useEffect(() => {
    const id = setInterval(() => {
      getLinearConfig()
        .then((cfg) => setConfig(cfg))
        .catch(() => {
          /* transient failures are fine — next tick retries */
        });
    }, INTEGRATION_STATUS_REFRESH_MS);
    return () => clearInterval(id);
  }, []);

  const update = useCallback(
    <K extends keyof FormState>(key: K, value: FormState[K]) =>
      setForm((prev) => ({ ...prev, [key]: value })),
    [],
  );

  const { saving, testing, handleTest, handleSave, handleDelete } = useSettingsActions({
    form,
    setConfig,
    setForm,
    setTestResult,
  });

  return {
    config,
    form,
    loading,
    saving,
    testing,
    testResult,
    health,
    teams,
    loadingTeams,
    update,
    handleTest,
    handleSave,
    handleDelete,
  };
}

function EnabledPill() {
  const { enabled, setEnabled } = useLinearEnabled();
  return (
    <div className="flex items-center gap-2 rounded-full border bg-muted/30 px-3 py-1">
      <Switch
        id="linear-enabled"
        checked={enabled}
        onCheckedChange={setEnabled}
        className="cursor-pointer"
      />
      <Label htmlFor="linear-enabled" className="text-xs cursor-pointer">
        {enabled ? "Enabled" : "Disabled"}
      </Label>
    </div>
  );
}

// LinearConnectionSection holds the install-wide credentials form. Linear has
// no per-workspace state to surface here today, so the page composes only this
// section.
export function LinearConnectionSection() {
  const s = useLinearSettings();
  const missingSecret = !s.config?.hasSecret && !s.form.secret;
  const disableSave = s.saving || missingSecret;
  const disableTest = missingSecret;

  return (
    <SettingsSection
      icon={<IconHexagon className="h-5 w-5" />}
      title="Linear integration"
      description="Connect Kandev to Linear with a personal API key. Credentials are stored encrypted server-side and shared across all workspaces."
      action={<EnabledPill />}
    >
      <Card>
        <CardContent className="space-y-4 pt-6">
          <IntegrationAuthStatusBanner health={s.health} />
          <SecretField
            form={s.form}
            loading={s.loading}
            update={s.update}
            hasSavedSecret={!!s.config?.hasSecret}
          />
          <TeamSelector
            form={s.form}
            loading={s.loading}
            update={s.update}
            hasSavedSecret={!!s.config?.hasSecret}
            teams={s.teams}
            loadingTeams={s.loadingTeams}
          />
          <TestResultAlert result={s.testResult} />
          <Separator />
          <ActionBar
            saving={s.saving}
            testing={s.testing}
            loading={s.loading}
            hasConfig={!!s.config}
            disableSave={disableSave}
            disableTest={disableTest}
            onTest={s.handleTest}
            onSave={s.handleSave}
            onDelete={s.handleDelete}
          />
        </CardContent>
      </Card>
    </SettingsSection>
  );
}

export function LinearIntegrationPage() {
  return (
    <div className="space-y-8">
      <LinearConnectionSection />
      <LinearIssueWatchersSection />
    </div>
  );
}