import { Component, createRef } from 'react';
import CloseOutlinedIcon from '@mui/icons-material/CloseOutlined';
import EditOutlinedIcon from '@mui/icons-material/EditOutlined';
import SaveOutlinedIcon from '@mui/icons-material/SaveOutlined';
import Alert from '@mui/material/Alert';
import Box from '@mui/material/Box';
import CircularProgress from '@mui/material/CircularProgress';
import IconButton from '@mui/material/IconButton';
import Paper from '@mui/material/Paper';
import Typography from '@mui/material/Typography';
import { injectMuiTheme } from './injectMuiTheme';
import { enqueueSnackbar } from 'notistack';
import { backendErrorFrom } from '../../utils/backendError';
import { panelTilePaperSx, TILE_ACTION_PADDING, tileActionIconSx, tileActionSx } from './panelTileLayout';

function valuesEqual(a, b) {
  return JSON.stringify(a) === JSON.stringify(b);
}

/**
 * Panel tile with centralized inline-edit chrome.
 * Pass `onSave` to enable edit UI; omit it for read-only tiles (no edit icon).
 */
class EditablePanelTileBase extends Component {
  constructor(props) {
    super(props);
    this.inputRef = createRef();
    this.state = {
      editing: false,
      draft: null,
      saving: false,
      error: null,
    };
  }

  componentDidUpdate(_prevProps, prevState) {
    if (!prevState.editing && this.state.editing) {
      this.inputRef.current?.focus();
    }
  }

  getSavedValue() {
    return this.props.value;
  }

  isDirty() {
    const { draft, editing } = this.state;
    if (!editing || draft == null) return false;
    if (this.props.isDirty) {
      return this.props.isDirty(draft, this.getSavedValue());
    }
    return !valuesEqual(draft, this.getSavedValue());
  }

  canSave() {
    const { draft, saving } = this.state;
    if (saving || !this.isDirty() || draft == null) return false;
    if (this.props.canSave) {
      return this.props.canSave(draft, this.getSavedValue());
    }
    return true;
  }

  handleStartEdit = (event) => {
    event.stopPropagation();
    this.setState({
      editing: true,
      draft: structuredClone(this.getSavedValue()),
      error: null,
    });
  };

  handleCancel = (event) => {
    event?.stopPropagation();
    this.setState({
      editing: false,
      draft: null,
      error: null,
    });
  };

  handleDraftChange = (nextDraft) => {
    this.setState({ draft: nextDraft, error: null });
  };

  handleEditKeyDown = (event) => {
    if (event.key === 'Escape') {
      event.preventDefault();
      event.stopPropagation();
      this.handleCancel();
      return;
    }

    if (event.key === 'Enter' && !event.shiftKey) {
      event.preventDefault();
      event.stopPropagation();
      if (this.canSave()) {
        void this.handleSave(event);
      }
    }
  };

  handleSave = async (event) => {
    event?.stopPropagation();
    if (!this.canSave()) return;

    const { onSave } = this.props;
    const { draft } = this.state;
    this.setState({ saving: true, error: null });

    try {
      await onSave(draft);
      this.setState({ editing: false, draft: null, saving: false, error: null });
      enqueueSnackbar('Gespeichert.', { variant: 'success' });
    } catch (err) {
      const normalized = backendErrorFrom(err);
      this.setState({ saving: false, error: normalized.message });
      enqueueSnackbar(normalized.message, { variant: 'error' });
    }
  };

  renderTitle() {
    const { title, onSave } = this.props;
    if (!title) return null;
    return (
      <Typography
        variant="overline"
        color="text.secondary"
        sx={{ display: 'block', mb: 1, pr: onSave ? 9 : 0 }}
      >
        {title}
      </Typography>
    );
  }

  renderActions() {
    const { onSave } = this.props;
    if (!onSave) return null;

    const { editing, saving } = this.state;
    const iconSx = tileActionIconSx;

    if (!editing) {
      return (
        <>
          <IconButton
            disabled
            aria-hidden
            tabIndex={-1}
            sx={{
              ...tileActionSx,
              right: 48,
              visibility: 'hidden',
              pointerEvents: 'none',
            }}
          >
            <SaveOutlinedIcon sx={iconSx} />
          </IconButton>
          <IconButton
            onClick={this.handleStartEdit}
            aria-label="Bearbeiten"
            sx={{ ...tileActionSx, right: 4 }}
          >
            <EditOutlinedIcon sx={iconSx} />
          </IconButton>
        </>
      );
    }

    return (
      <>
        <IconButton
          onClick={this.handleSave}
          disabled={!this.canSave()}
          aria-label="Speichern"
          color={this.canSave() ? 'primary' : 'default'}
          sx={{ ...tileActionSx, right: 48 }}
        >
          {saving ? (
            <CircularProgress size={22} color="inherit" />
          ) : (
            <SaveOutlinedIcon sx={iconSx} />
          )}
        </IconButton>
        <IconButton
          onClick={this.handleCancel}
          disabled={saving}
          aria-label="Abbrechen"
          sx={{ ...tileActionSx, right: 4 }}
        >
          <CloseOutlinedIcon sx={iconSx} />
        </IconButton>
      </>
    );
  }

  render() {
    const { onSave, theme, wide = 1, sx, minHeight = 120, tileKey, renderDisplay, renderEdit } =
      this.props;
    const { editing, draft, error } = this.state;
    const savedValue = this.getSavedValue();
    const pending = this.isDirty();
    const actionPadding = onSave ? TILE_ACTION_PADDING : 0;

    return (
      <Paper
        elevation={4}
        sx={panelTilePaperSx({
          wide,
          sx,
          minHeight,
          editing,
          pending,
          tileKey,
          theme,
        })}
      >
        {this.renderActions()}
        {this.renderTitle()}
        <Box
          sx={{
            flex: 1,
            minWidth: 0,
            pr: actionPadding,
            display: 'flex',
            alignItems: 'center',
          }}
          onKeyDown={editing ? this.handleEditKeyDown : undefined}
        >
          {editing && draft != null
            ? renderEdit(draft, this.handleDraftChange, this.inputRef)
            : renderDisplay(savedValue)}
        </Box>
        {error ? (
          <Alert severity="error" sx={{ mt: 1, py: 0 }}>
            {error}
          </Alert>
        ) : null}
      </Paper>
    );
  }
}

export const EditablePanelTile = injectMuiTheme(EditablePanelTileBase);