import { useCallback, useEffect, useRef, useState } from "react";
import {
  View,
  Text,
  FlatList,
  Pressable,
  ActivityIndicator,
  Alert,
} from "react-native";
import { router, useFocusEffect } from "expo-router";
import * as SecureStore from "expo-secure-store";
import { getIncidents, markIncidentPushed } from "@/lib/db";
import { pushIncidentToGit, loadGitConfig } from "@/lib/git";
import type { GitConfig } from "@/lib/git";
import { useSettings } from "@/hooks/useSettings";
import type { Incident } from "@/types/incident";
import { Colors } from "@/constants/theme";

function gitDotColor(inc: Incident): string {
  if (!inc.gitPushedAt) return Colors.danger;
  if (inc.gitPushedAt < inc.updatedAt) return Colors.warning;
  return Colors.success;
}

export default function HomeScreen() {
  const [incidents, setIncidents] = useState<Incident[]>([]);
  const [loading, setLoading] = useState(true);
  const [gitConfig, setGitConfig] = useState<GitConfig | null>(null);
  const [mdTemplate, setMdTemplate] = useState<string | undefined>(undefined);
  const [selectionMode, setSelectionMode] = useState(false);
  const [selected, setSelected] = useState<Set<string>>(new Set());
  const [bulkPushing, setBulkPushing] = useState(false);
  const [bulkProgress, setBulkProgress] = useState({ done: 0, total: 0 });
  const { settings, ready } = useSettings();
  const didRedirect = useRef(false);

  useEffect(() => {
    if (!ready || didRedirect.current) return;
    if (settings.homeView === "capture") {
      didRedirect.current = true;
      router.push("/new");
    }
  }, [ready, settings.homeView]);

  useFocusEffect(
    useCallback(() => {
      load();
    }, [])
  );

  async function load() {
    setLoading(true);
    const [data, config, tpl] = await Promise.all([
      getIncidents(100),
      loadGitConfig(),
      SecureStore.getItemAsync("md_template"),
    ]);
    setIncidents(data);
    setGitConfig(config);
    setMdTemplate(tpl ?? undefined);
    setLoading(false);
  }

  function enterSelectionMode(id: string) {
    setSelectionMode(true);
    setSelected(new Set([id]));
  }

  function toggleSelection(id: string) {
    setSelected((prev) => {
      const next = new Set(prev);
      if (next.has(id)) next.delete(id);
      else next.add(id);
      return next;
    });
  }

  function exitSelectionMode() {
    setSelectionMode(false);
    setSelected(new Set());
  }

  function selectAllUnpushed() {
    const ids = incidents
      .filter((i) => !i.gitPushedAt || i.gitPushedAt < i.updatedAt)
      .map((i) => i.id);
    setSelected(new Set(ids));
  }

  const unpushedCount = incidents.filter(
    (i) => !i.gitPushedAt || i.gitPushedAt < i.updatedAt
  ).length;

  async function handleBulkPush() {
    if (!gitConfig) {
      Alert.alert("Git not configured", "Set up a git provider in Settings first.");
      return;
    }
    const toPush = incidents.filter((i) => selected.has(i.id));
    if (toPush.length === 0) return;

    setBulkPushing(true);
    setBulkProgress({ done: 0, total: toPush.length });

    let ok = 0;
    let fail = 0;
    const now = new Date().toISOString();

    for (let i = 0; i < toPush.length; i++) {
      const inc = toPush[i];
      const result = await pushIncidentToGit(inc, gitConfig, mdTemplate);
      if (result.success) {
        await markIncidentPushed(inc.id);
        setIncidents((prev) =>
          prev.map((x) => (x.id === inc.id ? { ...x, gitPushedAt: now } : x))
        );
        ok++;
      } else {
        fail++;
      }
      setBulkProgress({ done: i + 1, total: toPush.length });
    }

    setBulkPushing(false);
    exitSelectionMode();

    if (fail === 0) {
      Alert.alert("Done", `${ok} incident${ok > 1 ? "s" : ""} pushed.`);
    } else {
      Alert.alert("Partial", `${ok} pushed, ${fail} failed.`);
    }
  }

  const gitConfigured = gitConfig !== null;

  return (
    <View style={{ flex: 1, backgroundColor: Colors.bg }}>
      {loading ? (
        <ActivityIndicator color={Colors.primary} style={{ marginTop: 48 }} />
      ) : (
        <FlatList
          data={incidents}
          keyExtractor={(item) => item.id}
          contentContainerStyle={{ padding: 16, paddingBottom: 96 }}
          ListEmptyComponent={
            <Text
              style={{
                color: Colors.textDim,
                textAlign: "center",
                marginTop: 64,
                fontSize: 15,
              }}
            >
              No incidents. Press + to log one.
            </Text>
          }
          renderItem={({ item }) => {
            const isSelected = selected.has(item.id);
            return (
              <Pressable
                onPress={() =>
                  selectionMode
                    ? toggleSelection(item.id)
                    : router.push(`/incident/${item.id}`)
                }
                onLongPress={() => !selectionMode && enterSelectionMode(item.id)}
                style={{
                  backgroundColor: isSelected ? Colors.surface2 : Colors.surface,
                  borderRadius: 8,
                  padding: 16,
                  marginBottom: 10,
                  borderLeftWidth: 3,
                  borderLeftColor:
                    item.status === "open" ? Colors.warning : Colors.success,
                  flexDirection: "row",
                  alignItems: "center",
                }}
              >
                <View style={{ flex: 1 }}>
                  <View
                    style={{
                      flexDirection: "row",
                      justifyContent: "space-between",
                      alignItems: "center",
                      marginBottom: 4,
                    }}
                  >
                    <Text
                      style={{
                        color: Colors.text1,
                        fontSize: 15,
                        fontWeight: "600",
                        flex: 1,
                      }}
                      numberOfLines={1}
                    >
                      {item.title || "Untitled"}
                    </Text>
                    <View style={{ flexDirection: "row", alignItems: "center", marginLeft: 8, gap: 6 }}>
                      {gitConfigured && !selectionMode && (
                        <View
                          style={{
                            width: 8,
                            height: 8,
                            borderRadius: 4,
                            backgroundColor: gitDotColor(item),
                          }}
                        />
                      )}
                      <View
                        style={{
                          backgroundColor:
                            item.status === "open" ? "#f59e0b20" : "#88D65620",
                          borderRadius: 4,
                          paddingHorizontal: 8,
                          paddingVertical: 2,
                        }}
                      >
                        <Text
                          style={{
                            color:
                              item.status === "open"
                                ? Colors.warning
                                : Colors.success,
                            fontSize: 11,
                            fontWeight: "700",
                            textTransform: "uppercase",
                          }}
                        >
                          {item.status}
                        </Text>
                      </View>
                    </View>
                  </View>
                  <Text
                    style={{ color: Colors.text2, fontSize: 12 }}
                    numberOfLines={1}
                  >
                    {item.service || "—"} · {item.createdAt.slice(0, 10)}
                  </Text>
                </View>

                {selectionMode && (
                  <View
                    style={{
                      width: 22,
                      height: 22,
                      borderRadius: 11,
                      borderWidth: 2,
                      borderColor: isSelected ? Colors.primary : Colors.border,
                      backgroundColor: isSelected ? Colors.primary : "transparent",
                      alignItems: "center",
                      justifyContent: "center",
                      marginLeft: 14,
                    }}
                  >
                    {isSelected && (
                      <Text
                        style={{ color: Colors.bg, fontSize: 12, fontWeight: "700" }}
                      >
                        ✓
                      </Text>
                    )}
                  </View>
                )}
              </Pressable>
            );
          }}
        />
      )}

      {/* FAB — hidden in selection mode */}
      {!selectionMode && (
        <Pressable
          onPress={() => router.push("/new")}
          style={{
            position: "absolute",
            bottom: 24,
            right: 24,
            width: 56,
            height: 56,
            borderRadius: 28,
            backgroundColor: Colors.primary,
            alignItems: "center",
            justifyContent: "center",
            elevation: 6,
          }}
        >
          <Text style={{ color: "#fff", fontSize: 28, lineHeight: 32 }}>+</Text>
        </Pressable>
      )}

      {/* Selection mode action bar */}
      {selectionMode && (
        <View
          style={{
            position: "absolute",
            bottom: 0,
            left: 0,
            right: 0,
            backgroundColor: Colors.surface,
            borderTopWidth: 1,
            borderTopColor: Colors.border,
            padding: 12,
            gap: 10,
          }}
        >
          {/* Quick-select shortcuts */}
          <View style={{ flexDirection: "row", gap: 8 }}>
            {gitConfigured && unpushedCount > 0 && (
              <Pressable
                onPress={selectAllUnpushed}
                style={{
                  flex: 1,
                  borderRadius: 6,
                  borderWidth: 1,
                  borderColor: Colors.border,
                  padding: 8,
                  alignItems: "center",
                }}
              >
                <Text style={{ color: Colors.text2, fontSize: 12, fontWeight: "600" }}>
                  Select unpushed ({unpushedCount})
                </Text>
              </Pressable>
            )}
            <Pressable
              onPress={() => setSelected(new Set(incidents.map((i) => i.id)))}
              style={{
                flex: 1,
                borderRadius: 6,
                borderWidth: 1,
                borderColor: Colors.border,
                padding: 8,
                alignItems: "center",
              }}
            >
              <Text style={{ color: Colors.text2, fontSize: 12, fontWeight: "600" }}>
                Select all ({incidents.length})
              </Text>
            </Pressable>
          </View>

          {/* Main actions */}
          <View style={{ flexDirection: "row", gap: 10 }}>
            <Pressable
              onPress={exitSelectionMode}
              style={{
                flex: 1,
                borderRadius: 8,
                borderWidth: 1,
                borderColor: Colors.border,
                padding: 14,
                alignItems: "center",
              }}
            >
              <Text style={{ color: Colors.text2, fontSize: 15, fontWeight: "600" }}>
                Cancel
              </Text>
            </Pressable>
            <Pressable
              onPress={handleBulkPush}
              disabled={selected.size === 0 || bulkPushing || !gitConfigured}
              style={{
                flex: 2,
                borderRadius: 8,
                backgroundColor:
                  selected.size === 0 || !gitConfigured
                    ? Colors.surface2
                    : Colors.primary,
                padding: 14,
                alignItems: "center",
              }}
            >
              <Text
                style={{
                  color:
                    selected.size === 0 || !gitConfigured
                      ? Colors.textDim
                      : Colors.bg,
                  fontSize: 15,
                  fontWeight: "700",
                }}
              >
                {bulkPushing
                  ? `Pushing ${bulkProgress.done}/${bulkProgress.total}…`
                  : `Push ${selected.size > 0 ? selected.size : ""} selected`}
              </Text>
            </Pressable>
          </View>
        </View>
      )}
    </View>
  );
}