"use client";

import { useState, useEffect, useCallback } from "react";
import { Card, Button, Modal, Input, CardSkeleton, ModelSelectModal } from "@/shared/components";
import { useCopyToClipboard } from "@/shared/hooks/useCopyToClipboard";
import { isOpenAICompatibleProvider, isAnthropicCompatibleProvider } from "@/shared/constants/providers";

// Validate combo name: only a-z, A-Z, 0-9, -, _
const VALID_NAME_REGEX = /^[a-zA-Z0-9_-]+$/;

export default function CombosPage() {
  const [combos, setCombos] = useState([]);
  const [loading, setLoading] = useState(true);
  const [showCreateModal, setShowCreateModal] = useState(false);
  const [editingCombo, setEditingCombo] = useState(null);
  const [activeProviders, setActiveProviders] = useState([]);
  const { copied, copy } = useCopyToClipboard();

  useEffect(() => {
    fetchData();
  }, []); // eslint-disable-line react-hooks/exhaustive-deps

  const fetchData = async () => {
    try {
      const [combosRes, providersRes] = await Promise.all([
        fetch("/api/combos"),
        fetch("/api/providers"),
      ]);
      const combosData = await combosRes.json();
      const providersData = await providersRes.json();
      
      if (combosRes.ok) setCombos(combosData.combos || []);
      if (providersRes.ok) {
        const active = (providersData.connections || []).filter(
          c => c.testStatus === "active" || c.testStatus === "success"
        );
        setActiveProviders(active);
      }
    } catch (error) {
      console.log("Error fetching data:", error);
    } finally {
      setLoading(false);
    }
  };

  const handleCreate = async (data) => {
    try {
      const res = await fetch("/api/combos", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(data),
      });
      if (res.ok) {
        await fetchData();
        setShowCreateModal(false);
      } else {
        const err = await res.json();
        alert(err.error || "Failed to create combo");
      }
    } catch (error) {
      console.log("Error creating combo:", error);
    }
  };

  const handleUpdate = async (id, data) => {
    try {
      const res = await fetch(`/api/combos/${id}`, {
        method: "PUT",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(data),
      });
      if (res.ok) {
        await fetchData();
        setEditingCombo(null);
      } else {
        const err = await res.json();
        alert(err.error || "Failed to update combo");
      }
    } catch (error) {
      console.log("Error updating combo:", error);
    }
  };

  const handleDelete = async (id) => {
    if (!confirm("Delete this combo?")) return;
    try {
      const res = await fetch(`/api/combos/${id}`, { method: "DELETE" });
      if (res.ok) {
        setCombos(combos.filter(c => c.id !== id));
      }
    } catch (error) {
      console.log("Error deleting combo:", error);
    }
  };

  if (loading) {
    return (
      <div className="flex flex-col gap-6">
        <CardSkeleton />
        <CardSkeleton />
      </div>
    );
  }

  return (
    <div className="flex flex-col gap-6">
      {/* Header */}
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-semibold">Combos</h1>
          <p className="text-sm text-text-muted mt-1">
            Create model combos with fallback support
          </p>
        </div>
        <Button icon="add" onClick={() => setShowCreateModal(true)}>
          Create Combo
        </Button>
      </div>

      {/* Combos List */}
      {combos.length === 0 ? (
        <Card>
          <div className="text-center py-12">
            <div className="inline-flex items-center justify-center w-16 h-16 rounded-full bg-primary/10 text-primary mb-4">
              <span className="material-symbols-outlined text-[32px]">layers</span>
            </div>
            <p className="text-text-main font-medium mb-1">No combos yet</p>
            <p className="text-sm text-text-muted mb-4">Create model combos with fallback support</p>
            <Button icon="add" onClick={() => setShowCreateModal(true)}>
              Create Combo
            </Button>
          </div>
        </Card>
      ) : (
        <div className="flex flex-col gap-4">
          {combos.map((combo) => (
            <ComboCard
              key={combo.id}
              combo={combo}
              copied={copied}
              onCopy={copy}
              onEdit={() => setEditingCombo(combo)}
              onDelete={() => handleDelete(combo.id)}
            />
          ))}
        </div>
      )}

      {/* Create Modal - Use key to force remount and reset state */}
      <ComboFormModal
        key="create"
        isOpen={showCreateModal}
        onClose={() => setShowCreateModal(false)}
        onSave={handleCreate}
        activeProviders={activeProviders}
      />

      {/* Edit Modal - Use key to force remount and reset state */}
      <ComboFormModal
        key={editingCombo?.id || "new"}
        isOpen={!!editingCombo}
        combo={editingCombo}
        onClose={() => setEditingCombo(null)}
        onSave={(data) => handleUpdate(editingCombo.id, data)}
        activeProviders={activeProviders}
      />
    </div>
  );
}

function ComboCard({ combo, copied, onCopy, onEdit, onDelete }) {
  return (
    <Card padding="sm" className="group">
      <div className="flex items-center justify-between">
        <div className="flex items-center gap-3 flex-1 min-w-0">
          <div className="size-8 rounded-lg bg-primary/10 flex items-center justify-center shrink-0">
            <span className="material-symbols-outlined text-primary text-[18px]">layers</span>
          </div>
          <div className="min-w-0 flex-1">
            <div className="flex items-center gap-2">
              <code className="text-sm font-medium font-mono truncate">{combo.name}</code>
              <button
                onClick={(e) => { e.stopPropagation(); onCopy(combo.name, `combo-${combo.id}`); }}
                className="p-0.5 hover:bg-black/5 dark:hover:bg-white/5 rounded text-text-muted hover:text-primary transition-colors opacity-0 group-hover:opacity-100"
                title="Copy combo name"
              >
                <span className="material-symbols-outlined text-[14px]">
                  {copied === `combo-${combo.id}` ? "check" : "content_copy"}
                </span>
              </button>
            </div>
            <div className="flex items-center gap-1 mt-0.5 flex-wrap">
              {combo.models.length === 0 ? (
                <span className="text-xs text-text-muted italic">No models</span>
              ) : (
                combo.models.slice(0, 3).map((model, index) => (
                  <code key={index} className="text-[10px] font-mono bg-black/5 dark:bg-white/5 px-1.5 py-0.5 rounded text-text-muted">
                    {model}
                  </code>
                ))
              )}
              {combo.models.length > 3 && (
                <span className="text-[10px] text-text-muted">+{combo.models.length - 3} more</span>
              )}
            </div>
          </div>
        </div>

        {/* Actions */}
        <div className="flex gap-0.5 opacity-0 group-hover:opacity-100 transition-opacity shrink-0">
          <button
            onClick={onEdit}
            className="p-1.5 hover:bg-black/5 dark:hover:bg-white/5 rounded text-text-muted hover:text-primary transition-colors"
            title="Edit"
          >
            <span className="material-symbols-outlined text-[16px]">edit</span>
          </button>
          <button
            onClick={onDelete}
            className="p-1.5 hover:bg-red-500/10 rounded text-red-500 transition-colors"
            title="Delete"
          >
            <span className="material-symbols-outlined text-[16px]">delete</span>
          </button>
        </div>
      </div>
    </Card>
  );
}

function ComboFormModal({ isOpen, combo, onClose, onSave, activeProviders }) {
  // Initialize state with combo values - key prop on parent handles reset on remount
  const [name, setName] = useState(combo?.name || "");
  const [models, setModels] = useState(combo?.models || []);
  const [showModelSelect, setShowModelSelect] = useState(false);
  const [saving, setSaving] = useState(false);
  const [nameError, setNameError] = useState("");
  const [modelAliases, setModelAliases] = useState({});
  const [providerNodes, setProviderNodes] = useState([]);

  const fetchModalData = async () => {
    try {
      const [aliasesRes, nodesRes] = await Promise.all([
        fetch("/api/models/alias"),
        fetch("/api/provider-nodes"),
      ]);

      if (!aliasesRes.ok || !nodesRes.ok) {
        throw new Error(`Failed to fetch data: aliases=${aliasesRes.status}, nodes=${nodesRes.status}`);
      }

      const [aliasesData, nodesData] = await Promise.all([
        aliasesRes.json(),
        nodesRes.json(),
      ]);
      setModelAliases(aliasesData.aliases || {});
      setProviderNodes(nodesData.nodes || []);
    } catch (error) {
      console.error("Error fetching modal data:", error);
    }
  };

  useEffect(() => {
    if (isOpen) fetchModalData();
  }, [isOpen]);

  const validateName = (value) => {
    if (!value.trim()) {
      setNameError("Name is required");
      return false;
    }
    if (!VALID_NAME_REGEX.test(value)) {
      setNameError("Only letters, numbers, - and _ allowed");
      return false;
    }
    setNameError("");
    return true;
  };

  const handleNameChange = (e) => {
    const value = e.target.value;
    setName(value);
    if (value) validateName(value);
    else setNameError("");
  };

  const handleAddModel = (model) => {
    if (!models.includes(model.value)) {
      setModels([...models, model.value]);
    }
  };

  const handleRemoveModel = (index) => {
    setModels(models.filter((_, i) => i !== index));
  };

  // Format model display name with readable provider name
  const formatModelDisplay = useCallback((modelValue) => {
    const parts = modelValue.split('/');
    if (parts.length !== 2) return modelValue;
    
    const [providerId, modelId] = parts;
    const matchedNode = providerNodes.find(node => node.id === providerId);
    
    if (matchedNode) {
      return `${matchedNode.name}/${modelId}`;
    }
    
    return modelValue;
  }, [providerNodes]);

  const handleMoveUp = (index) => {
    if (index === 0) return;
    const newModels = [...models];
    [newModels[index - 1], newModels[index]] = [newModels[index], newModels[index - 1]];
    setModels(newModels);
  };

  const handleMoveDown = (index) => {
    if (index === models.length - 1) return;
    const newModels = [...models];
    [newModels[index], newModels[index + 1]] = [newModels[index + 1], newModels[index]];
    setModels(newModels);
  };

  const handleSave = async () => {
    if (!validateName(name)) return;
    setSaving(true);
    await onSave({ name: name.trim(), models });
    setSaving(false);
  };

  const isEdit = !!combo;

  return (
    <>
      <Modal
        isOpen={isOpen}
        onClose={onClose}
        title={isEdit ? "Edit Combo" : "Create Combo"}
      >
        <div className="flex flex-col gap-3">
          {/* Name */}
          <div>
            <Input
              label="Combo Name"
              value={name}
              onChange={handleNameChange}
              placeholder="my-combo"
              error={nameError}
            />
            <p className="text-[10px] text-text-muted mt-0.5">
              Only letters, numbers, - and _ allowed
            </p>
          </div>

          {/* Models */}
          <div>
            <label className="text-sm font-medium mb-1.5 block">Models</label>

            {models.length === 0 ? (
              <div className="text-center py-4 border border-dashed border-black/10 dark:border-white/10 rounded-lg bg-black/[0.01] dark:bg-white/[0.01]">
                <span className="material-symbols-outlined text-text-muted text-xl mb-1">layers</span>
                <p className="text-xs text-text-muted">No models added yet</p>
              </div>
            ) : (
              <div className="flex flex-col gap-1 max-h-[200px] overflow-y-auto">
                {models.map((model, index) => (
                  <div
                    key={index}
                    className="group flex items-center gap-1.5 px-2 py-1 rounded-md bg-black/[0.02] dark:bg-white/[0.02] hover:bg-black/[0.04] dark:hover:bg-white/[0.04] transition-colors"
                  >
                    {/* Index badge */}
                    <span className="text-[10px] font-medium text-text-muted w-3 text-center shrink-0">{index + 1}</span>

                    {/* Model display - show readable name only */}
                    <div className="flex-1 min-w-0 px-1.5 py-0.5 text-xs text-text-main truncate">
                      {formatModelDisplay(model)}
                    </div>

                    {/* Priority arrows - horizontal, always visible */}
                    <div className="flex items-center gap-0.5">
                      <button
                        onClick={() => handleMoveUp(index)}
                        disabled={index === 0}
                        className={`p-0.5 rounded ${index === 0 ? "text-text-muted/20 cursor-not-allowed" : "text-text-muted hover:text-primary hover:bg-black/5 dark:hover:bg-white/5"}`}
                        title="Move up"
                      >
                        <span className="material-symbols-outlined text-[12px]">arrow_upward</span>
                      </button>
                      <button
                        onClick={() => handleMoveDown(index)}
                        disabled={index === models.length - 1}
                        className={`p-0.5 rounded ${index === models.length - 1 ? "text-text-muted/20 cursor-not-allowed" : "text-text-muted hover:text-primary hover:bg-black/5 dark:hover:bg-white/5"}`}
                        title="Move down"
                      >
                        <span className="material-symbols-outlined text-[12px]">arrow_downward</span>
                      </button>
                    </div>

                    {/* Remove - always visible */}
                    <button
                      onClick={() => handleRemoveModel(index)}
                      className="p-0.5 hover:bg-red-500/10 rounded text-text-muted hover:text-red-500 transition-all"
                      title="Remove"
                    >
                      <span className="material-symbols-outlined text-[12px]">close</span>
                    </button>
                  </div>
                ))}
              </div>
            )}

            {/* Add Model button - moved to bottom */}
            <button
              onClick={() => setShowModelSelect(true)}
              className="w-full mt-2 py-2 border border-dashed border-black/10 dark:border-white/10 rounded-lg text-xs text-text-muted hover:text-primary hover:border-primary/30 transition-colors flex items-center justify-center gap-1"
            >
              <span className="material-symbols-outlined text-[16px]">add</span>
              Add Model
            </button>
          </div>

          {/* Actions */}
          <div className="flex gap-2 pt-1">
            <Button onClick={onClose} variant="ghost" fullWidth size="sm">
              Cancel
            </Button>
            <Button
              onClick={handleSave}
              fullWidth
              size="sm"
              disabled={!name.trim() || !!nameError || saving}
            >
              {saving ? "Saving..." : isEdit ? "Save" : "Create"}
            </Button>
          </div>
        </div>
      </Modal>

      {/* Model Select Modal */}
      <ModelSelectModal
        isOpen={showModelSelect}
        onClose={() => setShowModelSelect(false)}
        onSelect={handleAddModel}
        activeProviders={activeProviders}
        modelAliases={modelAliases}
        title="Add Model to Combo"
      />
    </>
  );
}