import { useState, useEffect, useRef } from 'react';
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
import { faUpload } from '@fortawesome/pro-duotone-svg-icons';
import { Input } from '@/components/base/input/input';
import { Select } from '@/components/base/select/select';
import { Checkbox } from '@/components/base/checkbox/checkbox';
import { Button } from '@/components/base/buttons/button';
import { TopBar } from '@/components/layout/top-bar';
import { useThemeTokens } from '@/providers/theme-token-provider';
import type { ThemeTokens } from '@/providers/theme-token-provider';
import { notify } from '@/lib/toast';

const THEME_API_URL = import.meta.env.VITE_THEME_API_URL ?? import.meta.env.VITE_API_URL ?? 'http://localhost:4100';

const COLOR_STOPS = ['25', '50', '100', '200', '300', '400', '500', '600', '700', '800', '900', '950'];

const FONT_OPTIONS = [
    { id: "'Satoshi', 'Inter', -apple-system, sans-serif", label: 'Satoshi' },
    { id: "'General Sans', 'Inter', -apple-system, sans-serif", label: 'General Sans' },
    { id: "'Inter', -apple-system, sans-serif", label: 'Inter' },
    { id: "'DM Sans', 'Inter', sans-serif", label: 'DM Sans' },
    { id: "'Plus Jakarta Sans', 'Inter', sans-serif", label: 'Plus Jakarta Sans' },
    { id: "'Nunito Sans', 'Inter', sans-serif", label: 'Nunito Sans' },
    { id: "'Source Sans 3', 'Inter', sans-serif", label: 'Source Sans 3' },
    { id: "'Poppins', 'Inter', sans-serif", label: 'Poppins' },
    { id: "'Lato', 'Inter', sans-serif", label: 'Lato' },
    { id: "'Open Sans', 'Inter', sans-serif", label: 'Open Sans' },
    { id: "'Roboto', 'Inter', sans-serif", label: 'Roboto' },
    { id: "'Noto Sans', 'Inter', sans-serif", label: 'Noto Sans' },
];

const COLOR_PRESETS: Record<string, { label: string; colors: Record<string, string> }> = {
    blue: {
        label: 'Blue',
        colors: { '25': 'rgb(239 246 255)', '50': 'rgb(219 234 254)', '100': 'rgb(191 219 254)', '200': 'rgb(147 197 253)', '300': 'rgb(96 165 250)', '400': 'rgb(59 130 246)', '500': 'rgb(37 99 235)', '600': 'rgb(29 78 216)', '700': 'rgb(30 64 175)', '800': 'rgb(30 58 138)', '900': 'rgb(23 37 84)', '950': 'rgb(15 23 42)' },
    },
    teal: {
        label: 'Teal',
        colors: { '25': 'rgb(240 253 250)', '50': 'rgb(204 251 241)', '100': 'rgb(153 246 228)', '200': 'rgb(94 234 212)', '300': 'rgb(45 212 191)', '400': 'rgb(20 184 166)', '500': 'rgb(13 148 136)', '600': 'rgb(15 118 110)', '700': 'rgb(17 94 89)', '800': 'rgb(19 78 74)', '900': 'rgb(17 63 61)', '950': 'rgb(4 47 46)' },
    },
    violet: {
        label: 'Violet',
        colors: { '25': 'rgb(250 245 255)', '50': 'rgb(245 235 255)', '100': 'rgb(235 215 254)', '200': 'rgb(214 187 251)', '300': 'rgb(182 146 246)', '400': 'rgb(158 119 237)', '500': 'rgb(127 86 217)', '600': 'rgb(105 65 198)', '700': 'rgb(83 56 158)', '800': 'rgb(66 48 125)', '900': 'rgb(53 40 100)', '950': 'rgb(44 28 95)' },
    },
    rose: {
        label: 'Rose',
        colors: { '25': 'rgb(255 241 242)', '50': 'rgb(255 228 230)', '100': 'rgb(254 205 211)', '200': 'rgb(253 164 175)', '300': 'rgb(251 113 133)', '400': 'rgb(244 63 94)', '500': 'rgb(225 29 72)', '600': 'rgb(190 18 60)', '700': 'rgb(159 18 57)', '800': 'rgb(136 19 55)', '900': 'rgb(112 26 53)', '950': 'rgb(76 5 25)' },
    },
    emerald: {
        label: 'Emerald',
        colors: { '25': 'rgb(236 253 245)', '50': 'rgb(209 250 229)', '100': 'rgb(167 243 208)', '200': 'rgb(110 231 183)', '300': 'rgb(52 211 153)', '400': 'rgb(16 185 129)', '500': 'rgb(5 150 105)', '600': 'rgb(4 120 87)', '700': 'rgb(6 95 70)', '800': 'rgb(6 78 59)', '900': 'rgb(6 62 48)', '950': 'rgb(2 44 34)' },
    },
    amber: {
        label: 'Amber',
        colors: { '25': 'rgb(255 251 235)', '50': 'rgb(254 243 199)', '100': 'rgb(253 230 138)', '200': 'rgb(252 211 77)', '300': 'rgb(251 191 36)', '400': 'rgb(245 158 11)', '500': 'rgb(217 119 6)', '600': 'rgb(180 83 9)', '700': 'rgb(146 64 14)', '800': 'rgb(120 53 15)', '900': 'rgb(99 49 18)', '950': 'rgb(69 26 3)' },
    },
    slate: {
        label: 'Slate',
        colors: { '25': 'rgb(248 250 252)', '50': 'rgb(241 245 249)', '100': 'rgb(226 232 240)', '200': 'rgb(203 213 225)', '300': 'rgb(148 163 184)', '400': 'rgb(100 116 139)', '500': 'rgb(71 85 105)', '600': 'rgb(47 64 89)', '700': 'rgb(37 49 72)', '800': 'rgb(30 41 59)', '900': 'rgb(15 23 42)', '950': 'rgb(2 6 23)' },
    },
};

// Generate a full color scale from a single hex color
const hexToHsl = (hex: string): [number, number, number] => {
    const r = parseInt(hex.slice(1, 3), 16) / 255;
    const g = parseInt(hex.slice(3, 5), 16) / 255;
    const b = parseInt(hex.slice(5, 7), 16) / 255;
    const max = Math.max(r, g, b), min = Math.min(r, g, b);
    let h = 0, s = 0;
    const l = (max + min) / 2;
    if (max !== min) {
        const d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        if (max === r) h = ((g - b) / d + (g < b ? 6 : 0)) / 6;
        else if (max === g) h = ((b - r) / d + 2) / 6;
        else h = ((r - g) / d + 4) / 6;
    }
    return [h * 360, s * 100, l * 100];
};

const hslToRgb = (h: number, s: number, l: number): string => {
    h /= 360; s /= 100; l /= 100;
    let r: number, g: number, b: number;
    if (s === 0) { r = g = b = l; } else {
        const hue2rgb = (p: number, q: number, t: number) => {
            if (t < 0) t += 1; if (t > 1) t -= 1;
            if (t < 1/6) return p + (q - p) * 6 * t;
            if (t < 1/2) return q;
            if (t < 2/3) return p + (q - p) * (2/3 - t) * 6;
            return p;
        };
        const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
        const p = 2 * l - q;
        r = hue2rgb(p, q, h + 1/3);
        g = hue2rgb(p, q, h);
        b = hue2rgb(p, q, h - 1/3);
    }
    return `rgb(${Math.round(r * 255)} ${Math.round(g * 255)} ${Math.round(b * 255)})`;
};

const generatePalette = (hex: string): Record<string, string> => {
    const [h, s] = hexToHsl(hex);
    // Map each stop to a lightness value
    const stops: Record<string, number> = {
        '25': 97, '50': 94, '100': 89, '200': 80, '300': 68,
        '400': 56, '500': 46, '600': 38, '700': 31, '800': 26,
        '900': 20, '950': 13,
    };
    const result: Record<string, string> = {};
    for (const [stop, lightness] of Object.entries(stops)) {
        // Desaturate lighter stops slightly for natural feel
        const satAdj = lightness > 80 ? s * 0.6 : lightness > 60 ? s * 0.85 : s;
        result[stop] = hslToRgb(h, satAdj, lightness);
    }
    return result;
};

const rgbToHex = (rgb: string): string => {
    const match = rgb.match(/(\d+)\s+(\d+)\s+(\d+)/);
    if (!match) return '#3b82f6';
    const [, r, g, b] = match;
    return `#${[r, g, b].map(c => parseInt(c).toString(16).padStart(2, '0')).join('')}`;
};

const Section = ({ title, children }: { title: string; children: React.ReactNode }) => (
    <div className="rounded-xl border border-secondary bg-primary p-5">
        <h3 className="text-sm font-semibold text-primary mb-3">{title}</h3>
        <div className="flex flex-col gap-3">
            {children}
        </div>
    </div>
);

const FileUploadField = ({ label, value, onChange, accept }: { label: string; value: string; onChange: (v: string) => void; accept: string }) => {
    const inputRef = useRef<HTMLInputElement>(null);

    const handleFile = (e: React.ChangeEvent<HTMLInputElement>) => {
        const file = e.target.files?.[0];
        if (!file) return;
        const reader = new FileReader();
        reader.onload = () => onChange(reader.result as string);
        reader.readAsDataURL(file);
    };

    return (
        <div className="flex flex-col gap-1.5">
            <span className="text-xs font-medium text-secondary">{label}</span>
            <div className="flex items-center gap-3">
                {value && <img src={value} alt={label} className="size-10 rounded-lg border border-secondary object-contain" />}
                <button
                    type="button"
                    onClick={() => inputRef.current?.click()}
                    className="flex items-center gap-2 rounded-lg border border-secondary px-3 py-2 text-xs font-medium text-secondary hover:bg-secondary transition duration-100 ease-linear"
                >
                    <FontAwesomeIcon icon={faUpload} className="size-3" />
                    {value ? 'Change' : 'Upload'}
                </button>
                <input ref={inputRef} type="file" accept={accept} className="hidden" onChange={handleFile} />
                {value && <span className="text-xs text-tertiary truncate max-w-[200px]">{value.startsWith('data:') ? 'Uploaded file' : value}</span>}
            </div>
        </div>
    );
};

export const BrandingSettingsPage = () => {
    const { tokens, refresh } = useThemeTokens();
    const [form, setForm] = useState<ThemeTokens>(tokens);
    const [saving, setSaving] = useState(false);
    const [resetting, setResetting] = useState(false);

    useEffect(() => { setForm(tokens); }, [tokens]);

    const updateBrand = (key: keyof ThemeTokens['brand'], value: string) => {
        setForm(prev => ({ ...prev, brand: { ...prev.brand, [key]: value } }));
    };

    const updateColor = (stop: string, value: string) => {
        setForm(prev => ({ ...prev, colors: { ...prev.colors, brand: { ...prev.colors.brand, [stop]: value } } }));
    };

    const updateTypography = (key: keyof ThemeTokens['typography'], value: string) => {
        setForm(prev => ({ ...prev, typography: { ...prev.typography, [key]: value } }));
    };

    const updateLogin = (key: string, value: any) => {
        if (key === 'poweredBy.label') {
            setForm(prev => ({ ...prev, login: { ...prev.login, poweredBy: { ...prev.login.poweredBy, label: value } } }));
        } else if (key === 'poweredBy.url') {
            setForm(prev => ({ ...prev, login: { ...prev.login, poweredBy: { ...prev.login.poweredBy, url: value } } }));
        } else {
            setForm(prev => ({ ...prev, login: { ...prev.login, [key]: value } }));
        }
    };

    const updateSidebar = (key: keyof ThemeTokens['sidebar'], value: string) => {
        setForm(prev => ({ ...prev, sidebar: { ...prev.sidebar, [key]: value } }));
    };

    const updateQuickAction = (index: number, key: 'label' | 'prompt', value: string) => {
        setForm(prev => {
            const actions = [...prev.ai.quickActions];
            actions[index] = { ...actions[index], [key]: value };
            return { ...prev, ai: { quickActions: actions } };
        });
    };

    const addQuickAction = () => {
        setForm(prev => ({
            ...prev,
            ai: { quickActions: [...prev.ai.quickActions, { label: '', prompt: '' }] },
        }));
    };

    const removeQuickAction = (index: number) => {
        setForm(prev => ({
            ...prev,
            ai: { quickActions: prev.ai.quickActions.filter((_, i) => i !== index) },
        }));
    };

    const handleSave = async () => {
        setSaving(true);
        try {
            await fetch(`${THEME_API_URL}/api/config/theme`, { method: 'PUT', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(form) });
            await refresh();
            notify.success('Branding Saved', 'Theme updated successfully');
        } catch {
            notify.error('Save Failed', 'Could not update theme');
        } finally {
            setSaving(false);
        }
    };

    const handleReset = async () => {
        setResetting(true);
        try {
            await fetch(`${THEME_API_URL}/api/config/theme/reset`, { method: 'POST' });
            await refresh();
            notify.success('Branding Reset', 'Theme restored to defaults');
        } catch {
            notify.error('Reset Failed', 'Could not reset theme');
        } finally {
            setResetting(false);
        }
    };

    return (
        <>
            <TopBar title="Branding" subtitle="Customize the look and feel of your application" />

            <div className="flex flex-1 flex-col min-h-0 overflow-hidden">
            <div className="flex-1 overflow-y-auto p-6">
                <div className="grid grid-cols-2 gap-6">

                    {/* LEFT COLUMN */}
                    <div className="space-y-5">

                        {/* Brand Identity */}
                        <Section title="Brand Identity">
                            <div className="grid grid-cols-2 gap-3">
                                <Input size="sm" label="App Name" value={form.brand.name} onChange={(v) => updateBrand('name', v)} />
                                <Input size="sm" label="Hospital Name" value={form.brand.hospitalName} onChange={(v) => updateBrand('hospitalName', v)} />
                            </div>
                            <FileUploadField label="Logo" value={form.brand.logo} onChange={(v) => updateBrand('logo', v)} accept="image/*" />
                            <FileUploadField label="Favicon" value={form.brand.favicon} onChange={(v) => updateBrand('favicon', v)} accept="image/*,.ico" />
                        </Section>

                        {/* Typography */}
                        <Section title="Typography">
                            <div className="grid grid-cols-2 gap-3">
                                <Select size="sm" label="Body Font" items={FONT_OPTIONS} selectedKey={form.typography.body || null}
                                    onSelectionChange={(key) => updateTypography('body', key as string)} placeholder="Select body font">
                                    {(item) => <Select.Item id={item.id} label={item.label} />}
                                </Select>
                                <Select size="sm" label="Display Font" items={FONT_OPTIONS} selectedKey={form.typography.display || null}
                                    onSelectionChange={(key) => updateTypography('display', key as string)} placeholder="Select display font">
                                    {(item) => <Select.Item id={item.id} label={item.label} />}
                                </Select>
                            </div>
                        </Section>

                        {/* Login Page */}
                        <Section title="Login Page">
                            <div className="grid grid-cols-2 gap-3">
                                <Input size="sm" label="Title" value={form.login.title} onChange={(v) => updateLogin('title', v)} />
                                <Input size="sm" label="Subtitle" value={form.login.subtitle} onChange={(v) => updateLogin('subtitle', v)} />
                            </div>
                            <div className="flex items-center gap-6">
                                <Checkbox isSelected={form.login.showGoogleSignIn} onChange={(v) => updateLogin('showGoogleSignIn', v)} label="Google Sign-in" />
                                <Checkbox isSelected={form.login.showForgotPassword} onChange={(v) => updateLogin('showForgotPassword', v)} label="Forgot Password" />
                            </div>
                            <div className="grid grid-cols-2 gap-3">
                                <Input size="sm" label="Powered By Label" value={form.login.poweredBy.label} onChange={(v) => updateLogin('poweredBy.label', v)} />
                                <Input size="sm" label="Powered By URL" value={form.login.poweredBy.url} onChange={(v) => updateLogin('poweredBy.url', v)} />
                            </div>
                        </Section>

                        {/* Sidebar */}
                        <Section title="Sidebar">
                            <div className="grid grid-cols-2 gap-3">
                                <Input size="sm" label="Title" value={form.sidebar.title} onChange={(v) => updateSidebar('title', v)} />
                                <Input size="sm" label="Subtitle" value={form.sidebar.subtitle} onChange={(v) => updateSidebar('subtitle', v)} hint="{role} = user role" />
                            </div>
                        </Section>

                    </div>

                    {/* RIGHT COLUMN */}
                    <div className="space-y-5">

                        {/* Brand Colors */}
                        <Section title="Brand Colors">
                            <p className="text-xs text-tertiary -mt-1">Pick a base color or preset — the full palette generates automatically.</p>

                            {/* Color picker */}
                            <div className="flex items-center gap-3">
                                <label className="relative size-10 rounded-lg overflow-hidden border border-secondary cursor-pointer" style={{ backgroundColor: rgbToHex(form.colors.brand['500'] ?? 'rgb(37 99 235)') }}>
                                    <input
                                        type="color"
                                        value={rgbToHex(form.colors.brand['500'] ?? 'rgb(37 99 235)')}
                                        onChange={(e) => setForm(prev => ({ ...prev, colors: { brand: generatePalette(e.target.value) } }))}
                                        className="absolute inset-0 opacity-0 cursor-pointer"
                                    />
                                </label>
                                <div className="flex-1">
                                    <span className="text-xs font-medium text-secondary">Base Color</span>
                                    <p className="text-xs text-tertiary">{rgbToHex(form.colors.brand['500'] ?? 'rgb(37 99 235)')}</p>
                                </div>
                            </div>

                            {/* Presets */}
                            <div className="flex flex-wrap gap-2">
                                {Object.entries(COLOR_PRESETS).map(([key, preset]) => (
                                    <button
                                        key={key}
                                        onClick={() => setForm(prev => ({ ...prev, colors: { brand: { ...preset.colors } } }))}
                                        className="flex items-center gap-1.5 rounded-lg border border-secondary px-2.5 py-1.5 text-xs font-medium text-secondary hover:border-brand hover:text-brand-secondary transition duration-100 ease-linear"
                                    >
                                        <div className="flex h-3.5 w-10 rounded overflow-hidden">
                                            {['300', '500', '700'].map(s => (
                                                <div key={s} className="flex-1" style={{ backgroundColor: preset.colors[s] }} />
                                            ))}
                                        </div>
                                        {preset.label}
                                    </button>
                                ))}
                            </div>

                            {/* Generated palette preview */}
                            <div className="flex h-8 rounded-lg overflow-hidden border border-secondary">
                                {COLOR_STOPS.map(stop => (
                                    <div
                                        key={stop}
                                        className="flex-1 flex items-end justify-center pb-0.5"
                                        style={{ backgroundColor: form.colors.brand[stop] ?? '#ccc' }}
                                        title={`${stop}: ${form.colors.brand[stop] ?? ''}`}
                                    >
                                        <span className="text-[8px] font-bold" style={{ color: parseInt(stop) < 400 ? 'rgba(0,0,0,0.4)' : 'rgba(255,255,255,0.6)' }}>{stop}</span>
                                    </div>
                                ))}
                            </div>
                        </Section>

                        {/* AI Quick Actions */}
                        <Section title="AI Quick Actions">
                            <div className="space-y-2">
                                {form.ai.quickActions.map((action, i) => (
                                    <div key={i} className="flex items-start gap-2">
                                        <div className="flex-1 grid grid-cols-2 gap-2">
                                            <Input size="sm" placeholder="Label" value={action.label} onChange={(v) => updateQuickAction(i, 'label', v)} />
                                            <Input size="sm" placeholder="Prompt" value={action.prompt} onChange={(v) => updateQuickAction(i, 'prompt', v)} />
                                        </div>
                                        <Button size="sm" color="tertiary" onClick={() => removeQuickAction(i)} className="mt-1">Remove</Button>
                                    </div>
                                ))}
                            </div>
                            <Button size="sm" color="secondary" onClick={addQuickAction}>Add Quick Action</Button>
                        </Section>

                    </div>
                </div>

            </div>

            {/* Footer — pinned */}
            <div className="shrink-0 flex items-center justify-between px-6 py-4 border-t border-secondary">
                <Button size="sm" color="secondary" onClick={handleReset} isLoading={resetting}>
                    Reset to Defaults
                </Button>
                <Button size="md" color="primary" onClick={handleSave} isLoading={saving} showTextWhileLoading>
                    {saving ? 'Saving...' : 'Save Branding'}
                </Button>
            </div>
            </div>
        </>
    );
};