import { useState, useCallback, useEffect } from "react";
import { useParams, useNavigate } from "react-router";
import { Masthead } from "../components/Masthead";
import { ChainList } from "../components/chains/ChainList";
import { ChainEditor } from "../components/chains/ChainEditor";
import { useChains } from "../hooks/useChains";
import { useAuth } from "../contexts/AuthContext";
import type {
  ChainSummary,
  ChainWithContracts,
  ChainGraphResponse,
  CreateChainRequest,
} from "../lib/api";

export default function ChainsPage() {
  const { isAuthenticated, isAuthConfigured, isLoading: authLoading } = useAuth();
  const navigate = useNavigate();

  // Redirect to login if not authenticated (when auth is configured)
  useEffect(() => {
    if (!authLoading && isAuthConfigured && !isAuthenticated) {
      navigate("/login");
    }
  }, [authLoading, isAuthConfigured, isAuthenticated, navigate]);

  // Show loading while checking auth
  if (authLoading) {
    return (
      <div className="relative z-10 min-h-screen flex flex-col bg-[#0a1628]">
        <Masthead showNav />
        <main className="flex-1 flex items-center justify-center">
          <p className="text-[#7788aa] font-mono text-sm">Loading...</p>
        </main>
      </div>
    );
  }

  // Don't render if not authenticated (will redirect)
  if (isAuthConfigured && !isAuthenticated) {
    return null;
  }

  return <ChainsPageContent />;
}

function ChainsPageContent() {
  const { id } = useParams<{ id: string }>();
  const navigate = useNavigate();
  const {
    chains,
    loading,
    error,
    createNewChain,
    archiveExistingChain,
    getChainById,
    getGraph,
  } = useChains();

  const [chainDetail, setChainDetail] = useState<ChainWithContracts | null>(null);
  const [chainGraph, setChainGraph] = useState<ChainGraphResponse | null>(null);
  const [detailLoading, setDetailLoading] = useState(false);
  const [isCreating, setIsCreating] = useState(false);

  // Load chain detail when ID changes
  useEffect(() => {
    if (id) {
      setDetailLoading(true);
      Promise.all([getChainById(id), getGraph(id)]).then(([chain, graph]) => {
        setChainDetail(chain);
        setChainGraph(graph);
        setDetailLoading(false);
      });
    } else {
      setChainDetail(null);
      setChainGraph(null);
    }
  }, [id, getChainById, getGraph]);

  const handleSelect = useCallback(
    (chainId: string) => {
      navigate(`/chains/${chainId}`);
    },
    [navigate]
  );

  const handleBack = useCallback(() => {
    navigate("/chains");
  }, [navigate]);

  const handleCreate = useCallback(() => {
    setIsCreating(true);
  }, []);

  const handleCreateSubmit = useCallback(
    async (name: string, description: string) => {
      const data: CreateChainRequest = {
        name: name.trim(),
        description: description.trim() || undefined,
      };

      try {
        const result = await createNewChain(data);
        if (result) {
          setIsCreating(false);
          navigate(`/chains/${result.id}`);
        }
      } catch (err) {
        console.error("Failed to create chain:", err);
      }
    },
    [createNewChain, navigate]
  );

  const handleCreateCancel = useCallback(() => {
    setIsCreating(false);
  }, []);

  const handleArchive = useCallback(
    async (chain: ChainSummary) => {
      if (confirm(`Are you sure you want to archive "${chain.name}"?`)) {
        const success = await archiveExistingChain(chain.id);
        if (success && chain.id === id) {
          navigate("/chains");
        }
      }
    },
    [archiveExistingChain, id, navigate]
  );

  const handleRefresh = useCallback(async () => {
    if (id) {
      const [chain, graph] = await Promise.all([getChainById(id), getGraph(id)]);
      setChainDetail(chain);
      setChainGraph(graph);
    }
  }, [id, getChainById, getGraph]);

  const handleContractClick = useCallback(
    (contractId: string) => {
      navigate(`/contracts/${contractId}`);
    },
    [navigate]
  );

  return (
    <div className="relative z-10 min-h-screen flex flex-col bg-[#0a1628]">
      <Masthead showNav />
      <main className="flex-1 flex flex-col p-4 pt-2 gap-4 overflow-hidden">
        {error && (
          <div className="p-3 bg-red-400/10 border border-red-400/30 text-red-400 font-mono text-sm">
            {error}
          </div>
        )}

        {/* Create chain modal */}
        {isCreating && (
          <CreateChainModal
            onSubmit={handleCreateSubmit}
            onCancel={handleCreateCancel}
          />
        )}

        <div className="flex-1 grid grid-cols-[350px_1fr] gap-4 min-h-0">
          {/* Chain list */}
          <ChainList
            chains={chains}
            loading={loading}
            onSelect={handleSelect}
            onCreate={handleCreate}
            selectedId={id}
            onArchive={handleArchive}
          />

          {/* Chain detail/editor or empty state */}
          {chainDetail ? (
            <ChainEditor
              chain={chainDetail}
              graph={chainGraph}
              loading={detailLoading}
              onBack={handleBack}
              onRefresh={handleRefresh}
              onContractClick={handleContractClick}
            />
          ) : (
            <div className="panel h-full flex items-center justify-center">
              <div className="text-center">
                <p className="font-mono text-sm text-[#555] mb-4">
                  Select a chain or create a new one
                </p>
                <button
                  onClick={handleCreate}
                  className="px-4 py-2 font-mono text-xs text-[#dbe7ff] bg-[#0f3c78] border border-[#3f6fb3] hover:bg-[#153667] transition-colors uppercase"
                >
                  + New Chain
                </button>
              </div>
            </div>
          )}
        </div>
      </main>
    </div>
  );
}

interface CreateChainModalProps {
  onSubmit: (name: string, description: string) => void;
  onCancel: () => void;
}

function CreateChainModal({ onSubmit, onCancel }: CreateChainModalProps) {
  const [name, setName] = useState("");
  const [description, setDescription] = useState("");

  const handleSubmit = () => {
    if (name.trim()) {
      onSubmit(name.trim(), description.trim());
    }
  };

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 p-4">
      <div className="w-full max-w-lg p-6 bg-[#0a1628] border border-[rgba(117,170,252,0.3)]">
        <h3 className="font-mono text-sm text-[#75aafc] uppercase mb-4">
          Create Chain
        </h3>

        <div className="space-y-4">
          {/* Chain name */}
          <div>
            <label className="block font-mono text-xs text-[#8b949e] uppercase mb-1">
              Chain Name
            </label>
            <input
              type="text"
              value={name}
              onChange={(e) => setName(e.target.value)}
              placeholder="e.g., Feature Implementation"
              className="w-full px-3 py-2 bg-[#0d1b2d] border border-[#3f6fb3] text-[#dbe7ff] font-mono text-sm focus:outline-none focus:border-[#75aafc]"
              autoFocus
            />
          </div>

          {/* Description */}
          <div>
            <label className="block font-mono text-xs text-[#8b949e] uppercase mb-1">
              Description (optional)
            </label>
            <textarea
              value={description}
              onChange={(e) => setDescription(e.target.value)}
              placeholder="Describe what this chain accomplishes..."
              rows={3}
              className="w-full px-3 py-2 bg-[#0d1b2d] border border-[#3f6fb3] text-[#dbe7ff] font-mono text-sm focus:outline-none focus:border-[#75aafc] resize-none"
            />
          </div>

          <p className="font-mono text-xs text-[#8b949e]">
            A chain links multiple contracts together in a directed acyclic graph (DAG).
            Contracts can depend on each other, and dependent contracts start automatically
            when their dependencies complete.
          </p>

          {/* Actions */}
          <div className="flex gap-2 justify-end pt-2">
            <button
              onClick={onCancel}
              className="px-4 py-2 font-mono text-xs text-[#9bc3ff] hover:text-[#dbe7ff] transition-colors"
            >
              Cancel
            </button>
            <button
              onClick={handleSubmit}
              disabled={!name.trim()}
              className="px-4 py-2 font-mono text-xs text-[#dbe7ff] bg-[#0f3c78] border border-[#3f6fb3] hover:bg-[#153667] transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
            >
              Create
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}