"use client";

import * as React from "react";
import Link from "next/link";
import { cn, pluralize } from "@/lib/utils";
import type { RosterAssignment, RosterMember } from "@/app/(frontend)/roster/page";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { Building2Icon, CrownIcon, ListIcon, NetworkIcon, ShieldIcon } from "lucide-react";

const RosterDisplayContext = React.createContext<"lead" | "actual">("lead");

const TYPE_ORDER: Record<string, number> = {
  division: 0,
  squad: 1,
  team: 2,
  special: 3,
};

const TYPE_LABELS: Record<string, string> = {
  division: "Division",
  squad: "Squad",
  team: "Team",
  special: "Special",
};

type TreeNode = RosterAssignment & { children: TreeNode[]; members: RosterMember[] };

function buildTree(assignments: RosterAssignment[], members: RosterMember[]): TreeNode[] {
  const nodeMap = new Map<number, TreeNode>();
  for (const a of assignments) {
    nodeMap.set(a.id, { ...a, children: [], members: [] });
  }

  // Wire the explicit hierarchy from subAssignments. Drop any edge that
  // would create a cycle (a unit cannot contain itself) or that points at
  // an assignment that wasn't fetched.
  const childIds = new Set<number>();
  const visited = new Set<number>();
  const inStack = new Set<number>();
  const wire = (node: TreeNode): void => {
    if (visited.has(node.id) || inStack.has(node.id)) return;
    inStack.add(node.id);
    for (const subId of node.subAssignmentIds ?? []) {
      const child = nodeMap.get(subId);
      if (!child || inStack.has(child.id)) continue;
      node.children.push(child);
      childIds.add(child.id);
      wire(child);
    }
    inStack.delete(node.id);
    visited.add(node.id);
  };
  for (const node of nodeMap.values()) wire(node);

  const roots = assignments.filter((a) => !childIds.has(a.id)).map((a) => nodeMap.get(a.id)!);

  // Each node only holds the members/leader it claims directly — anyone a
  // descendant also claims renders at the deepest unit only.
  const descendantClaimed = (node: TreeNode): Set<number> => {
    const ids = new Set<number>();
    for (const child of node.children) {
      for (const id of [...child.memberIds, child.leaderId]) {
        if (id != null) ids.add(id);
      }
      for (const id of descendantClaimed(child)) ids.add(id);
    }
    return ids;
  };
  for (const a of assignments) {
    const node = nodeMap.get(a.id)!;
    const claimed = descendantClaimed(node);
    node.members = members.filter(
      (m) =>
        (a.memberIds.includes(m.user.id) || a.leaderId === m.user.id) && !claimed.has(m.user.id),
    );
  }

  const byOrder = (x: TreeNode, y: TreeNode) =>
    (TYPE_ORDER[x.type] ?? 99) - (TYPE_ORDER[y.type] ?? 99) || x.name.localeCompare(y.name);
  for (const node of nodeMap.values()) node.children.sort(byOrder);
  return roots.sort(byOrder);
}

function collectAllMembers(node: TreeNode): RosterMember[] {
  const result = [...node.members];
  for (const child of node.children) {
    result.push(...collectAllMembers(child));
  }
  return result;
}

// ─── Org Chart (top-down ORBAT tree) ────────────────────────────────

function OrgChartView({
  assignments,
  members,
}: {
  assignments: RosterAssignment[];
  members: RosterMember[];
}) {
  const roots = buildTree(assignments, members);
  const assignedIds = new Set(
    assignments.flatMap((a) => [...a.memberIds, a.leaderId]).filter(Boolean),
  );
  const unassigned = members.filter((m) => !assignedIds.has(m.user.id));

  return (
    <div className="flex flex-col gap-4">
      {roots.length > 0 ? (
        <div className="overflow-x-auto pb-2">
          <div className="flex flex-col items-center gap-4 min-w-max">
            {roots.map((root) => (
              <OrgChartNode key={root.id} node={root} depth={0} />
            ))}
          </div>
        </div>
      ) : (
        <p className="text-sm text-muted-foreground">No assignments configured.</p>
      )}

      {unassigned.length > 0 && (
        <div className="flex flex-col gap-2 mt-2">
          <h3 className="text-xs uppercase tracking-wider text-muted-foreground font-semibold">
            Unassigned
          </h3>
          <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-1.5">
            {unassigned.map((m) => (
              <MemberCard key={m.profileId} member={m} />
            ))}
          </div>
        </div>
      )}
    </div>
  );
}

function OrgChartNode({ node, depth }: { node: TreeNode; depth: number }) {
  const allMembers = collectAllMembers(node);
  const leader = node.leaderId ? allMembers.find((m) => m.user.id === node.leaderId) : null;
  const directMembers = node.members.filter((m) => m.user.id !== node.leaderId);

  return (
    <div className="flex flex-col items-center">
      <UnitBox
        node={node}
        depth={depth}
        leader={leader}
        directMembers={directMembers}
        memberCount={allMembers.length}
      />

      {node.children.length > 0 && (
        <>
          <div className="h-4 w-px bg-border" />
          <div className="flex items-start">
            {node.children.map((child) => (
              <div key={child.id} className="org-tree-child px-3">
                <OrgChartNode node={child} depth={depth + 1} />
              </div>
            ))}
          </div>
        </>
      )}
    </div>
  );
}

function UnitBox({
  node,
  depth,
  leader,
  directMembers,
  memberCount,
}: {
  node: TreeNode;
  depth: number;
  leader: RosterMember | null | undefined;
  directMembers: RosterMember[];
  memberCount: number;
}) {
  const depthBorders = ["border-l-blue-600", "border-l-amber-600", "border-l-emerald-600"];
  const borderClass = depthBorders[depth] ?? "border-l-zinc-600";

  return (
    <div
      className={cn(
        "border rounded-lg bg-muted/20 border-l-4 p-3 w-full min-w-56 max-w-lg",
        borderClass,
      )}
    >
      <div className="flex items-center gap-2 mb-2">
        <Building2Icon className="size-3.5 text-muted-foreground shrink-0" />
        <span className="text-sm font-semibold truncate">{node.name}</span>
        <span className="text-[10px] uppercase tracking-wider text-muted-foreground bg-muted px-1.5 py-0.5 rounded font-mono shrink-0">
          {TYPE_LABELS[node.type] ?? node.type}
        </span>
        {node.callsign && (
          <span className="text-[10px] text-muted-foreground font-mono shrink-0">
            [{node.callsign}]
          </span>
        )}
        <span className="text-[10px] text-muted-foreground ml-auto shrink-0">
          {memberCount} {pluralize(memberCount, "member")}
        </span>
      </div>

      {leader && (
        <div className="mb-2">
          <span className="text-[10px] uppercase tracking-wider text-muted-foreground flex items-center gap-1 mb-1">
            <CrownIcon className="size-3" /> Commanding
          </span>
          <MemberCard member={leader} />
        </div>
      )}

      {directMembers.length > 0 && (
        <div className="flex flex-col gap-1">
          {directMembers.map((m) => (
            <MemberCard key={m.profileId} member={m} />
          ))}
        </div>
      )}
    </div>
  );
}

// ─── By Assignment ──────────────────────────────────────────────────

function ByAssignmentView({
  assignments,
  members,
}: {
  assignments: RosterAssignment[];
  members: RosterMember[];
}) {
  const grouped = new Map<string, RosterMember[]>();
  for (const m of members) {
    const key = m.assignmentName ?? "__unassigned";
    const list = grouped.get(key) ?? [];
    list.push(m);
    grouped.set(key, list);
  }

  const sorted = [...grouped.entries()].sort(([a], [b]) => {
    if (a === "__unassigned") return 1;
    if (b === "__unassigned") return -1;
    const aType = assignments.find((asgn) => asgn.name === a)?.type ?? "";
    const bType = assignments.find((asgn) => asgn.name === b)?.type ?? "";
    return (TYPE_ORDER[aType] ?? 99) - (TYPE_ORDER[bType] ?? 99) || a.localeCompare(b);
  });

  return (
    <div className="flex flex-col gap-4">
      {sorted.map(([key, groupMembers]) => {
        const assignment = assignments.find((a) => a.name === key);
        return (
          <div key={key} className="flex flex-col gap-2">
            <div className="flex items-center gap-2">
              <Building2Icon className="size-3.5 text-muted-foreground" />
              <h3 className="text-sm font-semibold">
                {key === "__unassigned" ? "Unassigned" : key}
              </h3>
              {assignment && (
                <span className="text-[10px] uppercase tracking-wider text-muted-foreground bg-muted px-1.5 py-0.5 rounded font-mono">
                  {TYPE_LABELS[assignment.type] ?? assignment.type}
                </span>
              )}
              {assignment?.callsign && (
                <span className="text-[10px] text-muted-foreground font-mono">
                  [{assignment.callsign}]
                </span>
              )}
              <span className="text-[10px] text-muted-foreground ml-auto">
                {groupMembers.length}
              </span>
            </div>
            <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-1.5">
              {groupMembers.map((m) => (
                <MemberCard key={m.profileId} member={m} />
              ))}
            </div>
          </div>
        );
      })}
    </div>
  );
}

// ─── By Rank ────────────────────────────────────────────────────────

function ByRankView({ members }: { members: RosterMember[] }) {
  const grouped = new Map<string, RosterMember[]>();
  for (const m of members) {
    const list = grouped.get(m.rank.name) ?? [];
    list.push(m);
    grouped.set(m.rank.name, list);
  }

  const sorted = [...grouped.entries()].sort(([a], [b]) => a.localeCompare(b));

  return (
    <div className="flex flex-col gap-4">
      {sorted.map(([rankName, groupMembers]) => {
        const first = groupMembers[0];
        return (
          <div key={rankName} className="flex flex-col gap-2">
            <div className="flex items-center gap-2">
              {first.rank.insigniaUrl && (
                <img
                  src={first.rank.insigniaUrl}
                  alt={rankName}
                  className="size-5 object-contain"
                />
              )}
              <h3 className="text-sm font-semibold">{rankName}</h3>
              <span className="text-[10px] text-muted-foreground font-mono">
                ({first.rank.abbreviation})
              </span>
              <span className="text-[10px] text-muted-foreground ml-auto">
                {groupMembers.length}
              </span>
            </div>
            <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-1.5">
              {groupMembers.map((m) => (
                <MemberCard key={m.profileId} member={m} />
              ))}
            </div>
          </div>
        );
      })}
    </div>
  );
}

// ─── Alphabetical ───────────────────────────────────────────────────

function AlphabeticalView({ members }: { members: RosterMember[] }) {
  const sorted = [...members].sort((a, b) => a.user.displayName.localeCompare(b.user.displayName));

  return (
    <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-1.5">
      {sorted.map((m) => (
        <MemberCard key={m.profileId} member={m} />
      ))}
    </div>
  );
}

// ─── Member Card ────────────────────────────────────────────────────

function MemberCard({ member }: { member: RosterMember }) {
  const leadOrActual = React.useContext(RosterDisplayContext);
  const leadLabel = leadOrActual === "actual" ? "Actual" : "Lead";

  return (
    <Link
      href={`/profile/${member.user.username}`}
      className="flex items-center gap-2.5 rounded-md border border-border bg-muted/30 px-3 py-2 hover:bg-accent hover:border-accent-foreground/20 transition-colors"
    >
      {member.rank.insigniaUrl && (
        <img
          src={member.rank.insigniaUrl}
          alt={member.rank.name}
          className="size-5 object-contain shrink-0"
        />
      )}
      <div className="flex flex-col min-w-0 flex-1">
        <span className="text-sm font-medium truncate">{member.user.displayName}</span>
        <span className="text-[10px] text-muted-foreground font-mono truncate">
          {member.rank.abbreviation} · @{member.user.username}
        </span>
      </div>
      <div className="flex items-center gap-1.5 shrink-0">
        {member.isLeader && (
          <span className="text-[10px] uppercase tracking-wider text-amber-400 bg-amber-950/50 border border-amber-800/50 px-1.5 py-0.5 rounded font-semibold">
            {leadLabel}
          </span>
        )}
        {member.assignmentName && (
          <span className="text-[10px] text-muted-foreground bg-muted px-1.5 py-0.5 rounded font-mono hidden sm:block">
            {member.assignmentCallsign ? `[${member.assignmentCallsign}]` : member.assignmentName}
          </span>
        )}
      </div>
    </Link>
  );
}

// ─── Main RosterView ────────────────────────────────────────────────

export function RosterView({
  members,
  assignments,
  leadOrActual = "lead",
}: {
  members: RosterMember[];
  assignments: RosterAssignment[];
  leadOrActual?: "lead" | "actual";
}) {
  return (
    <RosterDisplayContext.Provider value={leadOrActual}>
      <Tabs defaultValue="org">
        <TabsList variant="line">
          <TabsTrigger value="org" className="gap-1.5">
            <NetworkIcon className="size-3" />
            Org Chart
          </TabsTrigger>
          <TabsTrigger value="assignment" className="gap-1.5">
            <Building2Icon className="size-3" />
            By Assignment
          </TabsTrigger>
          <TabsTrigger value="rank" className="gap-1.5">
            <ShieldIcon className="size-3" />
            By Rank
          </TabsTrigger>
          <TabsTrigger value="alpha" className="gap-1.5">
            <ListIcon className="size-3" />
            A–Z
          </TabsTrigger>
        </TabsList>

        <TabsContent value="org" className="overflow-x-scroll">
          <OrgChartView assignments={assignments} members={members} />
        </TabsContent>
        <TabsContent value="assignment">
          <ByAssignmentView assignments={assignments} members={members} />
        </TabsContent>
        <TabsContent value="rank">
          <ByRankView members={members} />
        </TabsContent>
        <TabsContent value="alpha">
          <AlphabeticalView members={members} />
        </TabsContent>
      </Tabs>
    </RosterDisplayContext.Provider>
  );
}