import { useEffect, useState, useCallback, type FormEvent } from "react";
import { useNavigate } from "react-router-dom";
import { Plus, ChevronUp, ChevronDown } from "lucide-react";
import { get, post, put, del } from "../api/client";
import { useAuth } from "../hooks/useAuth";
import type {
  Project,
  Item,
  CreateProjectRequest,
  UpdateProjectRequest,
} from "../api/types";

type Mode = "list" | "create" | "edit" | "delete";

interface ProjectWithCount extends Project {
  itemCount: number;
}

export function ProjectsPage() {
  const { user } = useAuth();
  const navigate = useNavigate();
  const isEditor = user?.role === "admin" || user?.role === "editor";

  const [projects, setProjects] = useState<ProjectWithCount[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const [mode, setMode] = useState<Mode>("list");
  const [editingProject, setEditingProject] = useState<ProjectWithCount | null>(
    null,
  );

  // Form state
  const [formCode, setFormCode] = useState("");
  const [formName, setFormName] = useState("");
  const [formDesc, setFormDesc] = useState("");
  const [formError, setFormError] = useState("");
  const [formSubmitting, setFormSubmitting] = useState(false);

  // Sort state
  const [sortKey, setSortKey] = useState<
    "code" | "name" | "itemCount" | "created_at"
  >("code");
  const [sortAsc, setSortAsc] = useState(true);

  const loadProjects = useCallback(async () => {
    try {
      const list = await get<Project[]>("/api/projects");
      const withCounts = await Promise.all(
        list.map(async (p) => {
          try {
            const items = await get<Item[]>(`/api/projects/${p.code}/items`);
            return { ...p, itemCount: items.length };
          } catch {
            return { ...p, itemCount: 0 };
          }
        }),
      );
      setProjects(withCounts);
      setError(null);
    } catch (e) {
      setError(e instanceof Error ? e.message : "Failed to load projects");
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    loadProjects();
  }, [loadProjects]);

  const openCreate = () => {
    setFormCode("");
    setFormName("");
    setFormDesc("");
    setFormError("");
    setMode("create");
  };

  const openEdit = (p: ProjectWithCount) => {
    setEditingProject(p);
    setFormCode(p.code);
    setFormName(p.name ?? "");
    setFormDesc(p.description ?? "");
    setFormError("");
    setMode("edit");
  };

  const openDelete = (p: ProjectWithCount) => {
    setEditingProject(p);
    setMode("delete");
  };

  const cancel = () => {
    setMode("list");
    setEditingProject(null);
    setFormError("");
  };

  const handleCreate = async (e: FormEvent) => {
    e.preventDefault();
    setFormError("");
    setFormSubmitting(true);
    try {
      const req: CreateProjectRequest = {
        code: formCode.toUpperCase(),
        name: formName || undefined,
        description: formDesc || undefined,
      };
      await post("/api/projects", req);
      cancel();
      await loadProjects();
    } catch (e) {
      setFormError(e instanceof Error ? e.message : "Failed to create project");
    } finally {
      setFormSubmitting(false);
    }
  };

  const handleEdit = async (e: FormEvent) => {
    e.preventDefault();
    if (!editingProject) return;
    setFormError("");
    setFormSubmitting(true);
    try {
      const req: UpdateProjectRequest = {
        name: formName,
        description: formDesc,
      };
      await put(`/api/projects/${editingProject.code}`, req);
      cancel();
      await loadProjects();
    } catch (e) {
      setFormError(e instanceof Error ? e.message : "Failed to update project");
    } finally {
      setFormSubmitting(false);
    }
  };

  const handleDelete = async () => {
    if (!editingProject) return;
    setFormSubmitting(true);
    try {
      await del(`/api/projects/${editingProject.code}`);
      cancel();
      await loadProjects();
    } catch (e) {
      setFormError(e instanceof Error ? e.message : "Failed to delete project");
    } finally {
      setFormSubmitting(false);
    }
  };

  const handleSort = (key: typeof sortKey) => {
    if (sortKey === key) {
      setSortAsc(!sortAsc);
    } else {
      setSortKey(key);
      setSortAsc(true);
    }
  };

  const sorted = [...projects].sort((a, b) => {
    let cmp = 0;
    if (sortKey === "code") cmp = a.code.localeCompare(b.code);
    else if (sortKey === "name")
      cmp = (a.name ?? "").localeCompare(b.name ?? "");
    else if (sortKey === "itemCount") cmp = a.itemCount - b.itemCount;
    else if (sortKey === "created_at")
      cmp = a.created_at.localeCompare(b.created_at);
    return sortAsc ? cmp : -cmp;
  });

  const formatDate = (s: string) => {
    const d = new Date(s);
    return d.toLocaleDateString("en-US", {
      year: "numeric",
      month: "short",
      day: "numeric",
    });
  };

  const sortArrow = (key: typeof sortKey) =>
    sortKey === key ? (
      <span
        style={{
          marginLeft: 4,
          display: "inline-flex",
          verticalAlign: "middle",
        }}
      >
        {sortAsc ? <ChevronUp size={14} /> : <ChevronDown size={14} />}
      </span>
    ) : null;

  if (loading)
    return <p style={{ color: "var(--ctp-subtext0)" }}>Loading projects...</p>;
  if (error) return <p style={{ color: "var(--ctp-red)" }}>Error: {error}</p>;

  return (
    <div>
      {/* Header */}
      <div
        style={{
          display: "flex",
          justifyContent: "space-between",
          alignItems: "center",
          marginBottom: "1rem",
        }}
      >
        <h2>Projects ({projects.length})</h2>
        {isEditor && mode === "list" && (
          <button
            onClick={openCreate}
            style={{
              ...btnPrimaryStyle,
              display: "inline-flex",
              alignItems: "center",
              gap: "0.25rem",
            }}
          >
            <Plus size={14} /> New Project
          </button>
        )}
      </div>

      {/* Create / Edit form */}
      {(mode === "create" || mode === "edit") && (
        <div style={formPaneStyle}>
          <div
            style={{
              ...formHeaderStyle,
              backgroundColor:
                mode === "create" ? "var(--ctp-green)" : "var(--ctp-blue)",
            }}
          >
            <strong>
              {mode === "create"
                ? "New Project"
                : `Edit ${editingProject?.code}`}
            </strong>
            <button onClick={cancel} style={formCloseStyle}>
              Cancel
            </button>
          </div>
          <form
            onSubmit={mode === "create" ? handleCreate : handleEdit}
            style={{ padding: "1rem" }}
          >
            {formError && <div style={errorBannerStyle}>{formError}</div>}
            {mode === "create" && (
              <div style={fieldStyle}>
                <label style={labelStyle}>
                  Code (2-10 characters, uppercase)
                </label>
                <input
                  className="silo-input"
                  type="text"
                  value={formCode}
                  onChange={(e) => setFormCode(e.target.value)}
                  placeholder="e.g., PROJ-A"
                  required
                  minLength={2}
                  maxLength={10}
                  style={{ ...inputStyle, textTransform: "uppercase" }}
                />
              </div>
            )}
            <div style={fieldStyle}>
              <label style={labelStyle}>Name</label>
              <input
                className="silo-input"
                type="text"
                value={formName}
                onChange={(e) => setFormName(e.target.value)}
                placeholder="Project name"
                style={inputStyle}
              />
            </div>
            <div style={fieldStyle}>
              <label style={labelStyle}>Description</label>
              <input
                className="silo-input"
                type="text"
                value={formDesc}
                onChange={(e) => setFormDesc(e.target.value)}
                placeholder="Project description"
                style={inputStyle}
              />
            </div>
            <div
              style={{
                display: "flex",
                gap: "0.5rem",
                justifyContent: "flex-end",
              }}
            >
              <button type="button" onClick={cancel} style={btnSecondaryStyle}>
                Cancel
              </button>
              <button
                type="submit"
                disabled={formSubmitting}
                style={btnPrimaryStyle}
              >
                {formSubmitting
                  ? "Saving..."
                  : mode === "create"
                    ? "Create Project"
                    : "Save Changes"}
              </button>
            </div>
          </form>
        </div>
      )}

      {/* Delete confirmation */}
      {mode === "delete" && editingProject && (
        <div style={formPaneStyle}>
          <div
            style={{ ...formHeaderStyle, backgroundColor: "var(--ctp-red)" }}
          >
            <strong>Delete Project</strong>
            <button onClick={cancel} style={formCloseStyle}>
              Cancel
            </button>
          </div>
          <div style={{ padding: "1.5rem", textAlign: "center" }}>
            {formError && <div style={errorBannerStyle}>{formError}</div>}
            <p>
              Are you sure you want to permanently delete project{" "}
              <strong style={{ color: "var(--ctp-peach)" }}>
                {editingProject.code}
              </strong>
              ?
            </p>
            <p
              style={{
                color: "var(--ctp-red)",
                marginTop: "0.5rem",
                fontSize: "var(--font-body)",
              }}
            >
              This action cannot be undone.
            </p>
            <div
              style={{
                display: "flex",
                gap: "0.5rem",
                justifyContent: "center",
                marginTop: "1.5rem",
              }}
            >
              <button onClick={cancel} style={btnSecondaryStyle}>
                Cancel
              </button>
              <button
                onClick={handleDelete}
                disabled={formSubmitting}
                style={btnDangerStyle}
              >
                {formSubmitting ? "Deleting..." : "Delete Permanently"}
              </button>
            </div>
          </div>
        </div>
      )}

      {/* Table */}
      <div style={tableContainerStyle}>
        <table style={{ width: "100%", borderCollapse: "collapse" }}>
          <thead>
            <tr>
              <th style={thStyle} onClick={() => handleSort("code")}>
                Code{sortArrow("code")}
              </th>
              <th style={thStyle} onClick={() => handleSort("name")}>
                Name{sortArrow("name")}
              </th>
              <th style={thStyle}>Description</th>
              <th style={thStyle} onClick={() => handleSort("itemCount")}>
                Items{sortArrow("itemCount")}
              </th>
              <th style={thStyle} onClick={() => handleSort("created_at")}>
                Created{sortArrow("created_at")}
              </th>
              {isEditor && <th style={thStyle}>Actions</th>}
            </tr>
          </thead>
          <tbody>
            {sorted.length === 0 ? (
              <tr>
                <td
                  colSpan={isEditor ? 6 : 5}
                  style={{
                    ...tdStyle,
                    textAlign: "center",
                    padding: "2rem",
                    color: "var(--ctp-subtext0)",
                  }}
                >
                  No projects found. Create your first project to start
                  organizing items.
                </td>
              </tr>
            ) : (
              sorted.map((p, i) => (
                <tr
                  key={p.id}
                  style={{
                    backgroundColor:
                      i % 2 === 0 ? "var(--ctp-base)" : "var(--ctp-surface0)",
                  }}
                >
                  <td style={tdStyle}>
                    <span
                      onClick={() =>
                        navigate(`/?project=${encodeURIComponent(p.code)}`)
                      }
                      style={{
                        color: "var(--ctp-peach)",
                        fontFamily: "'JetBrains Mono', monospace",
                        fontWeight: 500,
                        cursor: "pointer",
                      }}
                    >
                      {p.code}
                    </span>
                  </td>
                  <td style={tdStyle}>{p.name || "-"}</td>
                  <td style={tdStyle}>{p.description || "-"}</td>
                  <td style={tdStyle}>{p.itemCount}</td>
                  <td style={tdStyle}>{formatDate(p.created_at)}</td>
                  {isEditor && (
                    <td style={tdStyle}>
                      <div style={{ display: "flex", gap: "0.25rem" }}>
                        <button
                          onClick={() => openEdit(p)}
                          style={btnSmallStyle}
                        >
                          Edit
                        </button>
                        <button
                          onClick={() => openDelete(p)}
                          style={{
                            ...btnSmallStyle,
                            backgroundColor: "var(--ctp-surface2)",
                          }}
                        >
                          Delete
                        </button>
                      </div>
                    </td>
                  )}
                </tr>
              ))
            )}
          </tbody>
        </table>
      </div>
    </div>
  );
}

// Styles
const btnPrimaryStyle: React.CSSProperties = {
  padding: "0.5rem 1rem",
  borderRadius: "0.25rem",
  border: "none",
  backgroundColor: "var(--ctp-mauve)",
  color: "var(--ctp-crust)",
  fontWeight: 500,
  fontSize: "0.75rem",
  cursor: "pointer",
};

const btnSecondaryStyle: React.CSSProperties = {
  padding: "0.5rem 1rem",
  borderRadius: "0.25rem",
  border: "none",
  backgroundColor: "var(--ctp-surface1)",
  color: "var(--ctp-text)",
  fontWeight: 500,
  fontSize: "0.75rem",
  cursor: "pointer",
};

const btnDangerStyle: React.CSSProperties = {
  padding: "0.5rem 1rem",
  borderRadius: "0.25rem",
  border: "none",
  backgroundColor: "var(--ctp-red)",
  color: "var(--ctp-crust)",
  fontWeight: 500,
  fontSize: "0.75rem",
  cursor: "pointer",
};

const btnSmallStyle: React.CSSProperties = {
  padding: "0.25rem 0.5rem",
  borderRadius: "0.25rem",
  border: "none",
  backgroundColor: "var(--ctp-surface1)",
  color: "var(--ctp-text)",
  fontWeight: 500,
  fontSize: "0.75rem",
  cursor: "pointer",
};

const formPaneStyle: React.CSSProperties = {
  backgroundColor: "var(--ctp-surface0)",
  borderRadius: "0.5rem",
  marginBottom: "1rem",
  overflow: "hidden",
};

const formHeaderStyle: React.CSSProperties = {
  display: "flex",
  justifyContent: "space-between",
  alignItems: "center",
  padding: "0.5rem 1rem",
  color: "var(--ctp-crust)",
  fontSize: "var(--font-body)",
};

const formCloseStyle: React.CSSProperties = {
  background: "none",
  border: "none",
  color: "inherit",
  cursor: "pointer",
  fontSize: "0.75rem",
  fontWeight: 500,
  borderRadius: "0.25rem",
};

const errorBannerStyle: React.CSSProperties = {
  color: "var(--ctp-red)",
  background: "rgba(243, 139, 168, 0.1)",
  border: "1px solid rgba(243, 139, 168, 0.2)",
  padding: "0.5rem 0.75rem",
  borderRadius: "0.5rem",
  marginBottom: "0.75rem",
  fontSize: "var(--font-body)",
};

const fieldStyle: React.CSSProperties = {
  marginBottom: "0.75rem",
};

const labelStyle: React.CSSProperties = {
  display: "block",
  marginBottom: "0.25rem",
  fontWeight: 500,
  color: "var(--ctp-subtext1)",
  fontSize: "var(--font-body)",
};

const inputStyle: React.CSSProperties = {
  width: "100%",
  padding: "0.5rem 0.75rem",
  backgroundColor: "var(--ctp-base)",
  border: "1px solid var(--ctp-surface1)",
  borderRadius: "0.5rem",
  color: "var(--ctp-text)",
  fontSize: "var(--font-body)",
  boxSizing: "border-box",
};

const tableContainerStyle: React.CSSProperties = {
  backgroundColor: "var(--ctp-surface0)",
  borderRadius: "0.75rem",
  padding: "0.5rem",
  overflowX: "auto",
};

const thStyle: React.CSSProperties = {
  padding: "0.5rem 0.75rem",
  textAlign: "left",
  borderBottom: "1px solid var(--ctp-surface1)",
  color: "var(--ctp-overlay1)",
  fontWeight: 600,
  fontSize: "var(--font-table)",
  textTransform: "uppercase",
  letterSpacing: "0.05em",
  cursor: "pointer",
  userSelect: "none",
};

const tdStyle: React.CSSProperties = {
  padding: "0.25rem 0.75rem",
  borderBottom: "1px solid var(--ctp-surface1)",
  fontSize: "var(--font-body)",
};