/**
 * ThemeService — Palette and theme management
 * 
 * 8 Built-in Palettes (curated, no near-duplicates):
 * - Klonkt (default, navy + gold brand)
 * - Paper (minimalist white)
 * - Forest (greens)
 * - Sunset (pink)
 * - Sand (warm paper, clay accent — key 'cream')
 * - Lilac (purple)
 * - Ocean (klonkt navy + blue accent)
 * - Candy (klonkt navy + candy-red accent)
 *
 * Dark/Light mode toggle stored per user
 */

class ThemeService {
  // Paper/ink values map 1-to-1 from the [data-palette] CSS in style.css (= what
  // is ACTUALLY applied); the accent dot is a representative color per palette.
  static PALETTES = {
    // Brand default — matches klonkt.com (dark blue + gold).
    klonkt: {
      name: 'Klonkt',
      light: { paper: '#f3f1ea', ink: '#11141c', accent: '#c98a2a' },
      dark: { paper: '#0b0d12', ink: '#f3f1ea', accent: '#e8b04b' }
    },
    paper: {
      name: 'Paper',
      light: { paper: '#ffffff', ink: '#09090b', accent: '#000000' },
      dark: { paper: '#0a0a0a', ink: '#fafafa', accent: '#ffffff' }
    },
    forest: {
      name: 'Forest',
      light: { paper: '#f2f6ed', ink: '#1a2e15', accent: '#4d7c2a' },
      dark: { paper: '#0d1f12', ink: '#dcf2d0', accent: '#6fae3f' }
    },
    sunset: {
      name: 'Sunset',
      light: { paper: '#fdf4f3', ink: '#2e1618', accent: '#d6477f' },
      dark: { paper: '#1f0a14', ink: '#fce7f3', accent: '#f06fa3' }
    },
    // Warm paper — soft off-white + clay accent (deliberately NOT bright yellow).
    // key stays 'cream' (DB-safe).
    cream: {
      name: 'Sand',
      light: { paper: '#f7f3ec', ink: '#232019', accent: '#bf6a45' },
      dark: { paper: '#14120d', ink: '#efe9dd', accent: '#d6845f' }
    },
    // Ocean & Candy = the klonkt palette (navy + off-white) with a different accent.
    ocean: {
      name: 'Ocean',
      light: { paper: '#f3f1ea', ink: '#11141c', accent: '#1d6fe0' },
      dark: { paper: '#0b0d12', ink: '#f3f1ea', accent: '#4f9bff' }
    },
    candy: {
      name: 'Candy',
      light: { paper: '#f3f1ea', ink: '#11141c', accent: '#e11d48' },
      dark: { paper: '#0b0d12', ink: '#f3f1ea', accent: '#fb5c7d' }
    },
    lilac: {
      name: 'Lilac',
      light: { paper: '#faf4fb', ink: '#2a1830', accent: '#a855f7' },
      dark: { paper: '#170a1c', ink: '#f3e2f7', accent: '#c084fc' }
    }
  };

  /**
   * Curated accent palette — admins pick one of these instead of a free-form
   * hex picker. Keeps the brand consistent and avoids unreadable combinations.
   * Each color works against both light and dark themes.
   */
  // Balanced across the color wheel — fewer greens/blues (4 of 12),
  // more warm + purple/pink variation. All readable on both light and dark.
  static ACCENTS = [
    { key: 'klonkt',  name: 'Klonkt-geel', color: '#e8b04b' },
    { key: 'red',     name: 'Candy-rood', color: '#e11d48' },
    { key: 'amber',   name: 'Amber',     color: '#d97706' },
    { key: 'forest',  name: 'Groen',     color: '#16a34a' },
    { key: 'teal',    name: 'Turquoise', color: '#0d9488' },
    { key: 'ocean',   name: 'Blauw',     color: '#2563eb' },
    { key: 'indigo',  name: 'Indigo',    color: '#4f46e5' },
    { key: 'violet',  name: 'Violet',    color: '#7c3aed' },
    { key: 'plum',    name: 'Magenta',   color: '#c026d3' },
    { key: 'pink',    name: 'Roze',      color: '#db2777' },
  ];

  static listAccents() {
    return this.ACCENTS;
  }

  /**
   * Validate an accent color. Returns the canonical hex if it's in the curated
   * set (case-insensitive match), or null if it's not. Server-side validation
   * uses this so we never persist arbitrary hex from the form.
   */
  static validateAccent(hex) {
    if (!hex || typeof hex !== 'string') return null;
    const target = hex.trim().toLowerCase();
    const found = this.ACCENTS.find(a => a.color.toLowerCase() === target);
    return found ? found.color : null;
  }

  /**
   * Get palette data
   */
  static getPalette(paletteKey) {
    return this.PALETTES[paletteKey] || this.PALETTES.klonkt;
  }

  /**
   * Get all available palettes (with full color data so a picker UI can
   * render true previews of paper/ink/accent for both light and dark).
   */
  static listPalettes() {
    return Object.entries(this.PALETTES).map(([key, data]) => ({
      key,
      name: data.name,
      light: data.light,
      dark: data.dark,
    }));
  }

  /**
   * Generate CSS variables for palette + theme
   */
  static generateCSSVars(paletteKey, theme = 'dark', accentColor = null) {
    const palette = this.getPalette(paletteKey);
    const colors = theme === 'dark' ? palette.dark : palette.light;
    const accent = accentColor || colors.accent;

    return `
      :root {
        --palette: ${paletteKey};
        --theme: ${theme};
        --paper: ${colors.paper};
        --ink: ${colors.ink};
        --accent: ${accent};
      }
    `.trim();
  }

  /**
   * Update user's theme preference
   */
  static updateUserTheme(db, userId, theme, palette) {
    if (!['dark', 'light'].includes(theme)) {
      throw new Error('Invalid theme. Must be "dark" or "light"');
    }
    if (!this.PALETTES[palette]) {
      throw new Error('Invalid palette');
    }

    db.prepare(`
      UPDATE users SET theme = ?, palette = ? WHERE id = ?
    `).run(theme, palette, userId);
  }

  /**
   * Update site's palette + accent
   */
  static updateSitePalette(db, siteId, paletteKey, accentColor) {
    if (!this.PALETTES[paletteKey]) {
      throw new Error('Invalid palette');
    }
    if (!/^#[0-9a-f]{6}$/i.test(accentColor)) {
      throw new Error('Invalid accent color. Must be hex #RRGGBB');
    }

    db.prepare(`
      UPDATE sites SET palette = ?, accent = ? WHERE id = ?
    `).run(paletteKey, accentColor, siteId);
  }

  /**
   * Generate full HTML theme meta tags
   */
  static generateThemeMeta(userTheme, userPalette, siteTheme, siteAccent) {
    const theme = userTheme || siteTheme || 'dark';
    const palette = userPalette || 'klonkt';
    const accent = siteAccent || '#e8b04b';
    const paletteData = this.getPalette(palette);
    const colors = theme === 'dark' ? paletteData.dark : paletteData.light;

    return {
      colorScheme: 'dark light',
      themeColor: accent,
      appleMobileWebAppStatusBarStyle: 'black-translucent',
      cssVars: this.generateCSSVars(palette, theme, accent),
      inline: `
        <style>
          html {
            color-scheme: ${theme === 'dark' ? 'dark light' : 'light dark'};
          }
          :root {
            --paper: ${colors.paper};
            --ink: ${colors.ink};
            --accent: ${accent};
          }
        </style>
        <script>
          // Apply theme ASAP (before paint) to avoid flash
          (function() {
            try {
              const t = localStorage.getItem('pcms-theme') || '${theme}';
              const p = localStorage.getItem('pcms-palette') || '${palette}';
              document.documentElement.setAttribute('data-theme', t);
              document.documentElement.setAttribute('data-palette', p);
            } catch(e) {}
          })();
        </script>
      `.trim()
    };
  }
}

export default ThemeService;