import styled from "styled-components";

import { useEffect, useState } from "preact/hooks";

import { dispatch } from "../../../redux";

import { Theme, generateVariables } from "../../../context/Theme";

import Tip from "../../../components/ui/Tip";
import previewPath from "../assets/preview.svg";

import { GIT_REVISION } from "../../../revision";

export const fetchManifest = (): Promise<Manifest> =>
    fetch(`${import.meta.env.VITE_THEMES_URL}/manifest.json`).then((res) =>
        res.json(),
    );

export const fetchTheme = (slug: string): Promise<Theme> =>
    fetch(`${import.meta.env.VITE_THEMES_URL}/theme_${slug}.json`).then((res) =>
        res.json(),
    );

interface ThemeMetadata {
    name: string;
    creator: string;
    commit?: string;
    description: string;
}

type Manifest = {
    generated: string;
    themes: Record<string, ThemeMetadata>;
};

// TODO: ability to preview / display the settings set like in the appearance pane
const ThemeInfo = styled.article`
    display: grid;
    grid:
        "preview name creator" min-content
        "preview desc desc" 1fr
        / 200px 1fr 1fr;

    gap: 0.5rem 1rem;
    padding: 1rem;
    border-radius: var(--border-radius);
    background: var(--secondary-background);

    &[data-loaded] {
        .preview {
            opacity: 1;
        }
    }

    .preview {
        grid-area: preview;
        aspect-ratio: 323 / 202;

        background-color: var(--secondary-background);
        border-radius: calc(var(--border-radius) / 2);

        // prep style for later
        outline: 3px solid transparent;

        // hide random svg parts, crop border on firefox
        overflow: hidden;

        // hide until loaded
        opacity: 0;

        // style button
        border: 0;
        margin: 0;
        padding: 0;

        transition: 0.25s opacity, 0.25s outline;

        > * {
            grid-area: 1 / 1;
        }

        svg {
            height: 100%;
            width: 100%;
            object-fit: contain;
        }

        &:hover,
        &:active,
        &:focus-visible {
            outline: 3px solid var(--tertiary-background);
        }
    }

    .name {
        grid-area: name;
        margin: 0;
    }

    .creator {
        grid-area: creator;
        justify-self: end;
        font-size: 0.75rem;
    }

    .description {
        grid-area: desc;
    }
`;

const ThemeList = styled.div`
    display: grid;
    gap: 1rem;
`;

const ThemedSVG = styled.svg<{ theme: Theme }>`
    ${(props) => props.theme && generateVariables(props.theme)}
`;

type ThemePreviewProps = Omit<JSX.HTMLAttributes<SVGSVGElement>, "as"> & {
    slug?: string;
    theme?: Theme;
    onThemeLoaded?: (theme: Theme) => void;
};

const ThemePreview = ({ theme, ...props }: ThemePreviewProps) => {
    return (
        <ThemedSVG
            {...props}
            theme={theme}
            width="323"
            height="202"
            aria-hidden="true"
            data-loaded={!!theme}>
            <use href={`${previewPath}#preview`} width="100%" height="100%" />
        </ThemedSVG>
    );
};

const ThemeShopRoot = styled.div`
    display: grid;
    gap: 1rem;
`;

export function ThemeShop() {
    // setThemeList is for adding more / lazy loading in the future
    const [themeList, setThemeList] = useState<
        [string, ThemeMetadata][] | null
    >(null);
    const [themeData, setThemeData] = useState<Record<string, Theme>>({});

    async function fetchThemeList() {
        const manifest = await fetchManifest();
        setThemeList(
            Object.entries(manifest.themes).filter((x) =>
                x[1].commit ? x[1].commit === GIT_REVISION : true,
            ),
        );
    }

    async function getTheme(slug: string) {
        const theme = await fetchTheme(slug);
        setThemeData((data) => ({ ...data, [slug]: theme }));
    }

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

    useEffect(() => {
        themeList?.forEach(([slug]) => {
            getTheme(slug);
        });
    }, [themeList]);

    return (
        <ThemeShopRoot>
            <Tip warning hideSeparator>
                This section is under construction.
            </Tip>
            <ThemeList>
                {themeList?.map(([slug, theme]) => (
                    <ThemeInfo
                        key={slug}
                        data-loaded={Reflect.has(themeData, slug)}>
                        <h2 class="name">{theme.name}</h2>
                        {/* Maybe id's of the users should be included as well / instead? */}
                        <div class="creator">by {theme.creator}</div>
                        <div class="description">{theme.description}</div>
                        <button
                            class="preview"
                            onClick={() =>
                                dispatch({
                                    type: "SETTINGS_SET_THEME",
                                    theme: {
                                        custom: themeData[slug],
                                    },
                                })
                            }>
                            <ThemePreview slug={slug} theme={themeData[slug]} />
                        </button>
                    </ThemeInfo>
                ))}
            </ThemeList>
        </ThemeShopRoot>
    );
}