/* app/book.c — 书桥实现（见 app/book.h）：把 rd_src（TXT/FB2/EPUB/MOBI 段契约 + CBZ 图页）
 * + engine(FreeType/rdimg) 串成「一本书」。
 *
 * 文本格式：build_index 逐段 rd_src_next → 每段 utf8→码点→rd_layout → 页索引（flat：段+段内字符偏移）
 * （即 rdtxt 同款 UTF-8 段契约喂排版器）；渲染按段重显。锚定 (段,字符偏移) 与字号无关。
 * CBZ：纯图页，npages=图片数，render 用 rdimg 解码+降采样写内容区。
 */
#include "book.h"
#include "rdsrc.h"
#include "rdtxt.h"
#include "rdlayout.h"
#include "rdimg.h"
#include "../engine/rdft.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct seg {
    int page_start;   /* 全局页表起点 */
    int page_count;   /* 本段页数 */
} seg_t;

struct rd_book {
    char        path[400];
    char        font[400];
    char        base[256];
    const char *encname;
    rdft       *ft;
    rd_src     *src;
    rd_fmt_t    fmt;
    int         is_img;   /* 1=CBZ 图片书 */

    int fs, ls, pw, ph, mx, my, top;
    int content_w, content_h;

    seg_t        *segs;  int nsegs;
    rd_book_page *pages; int npages;   /* flat 页表（文本） */
    int          cur;

    /* 当前渲染段复用缓冲 */
    uint8_t  *seg_utf8;  size_t seg_utf8_cap;
    uint32_t *seg_cps;   size_t seg_cps_n, seg_cps_cap;
    rd_line  *seg_lines; rd_page *seg_pages; int seg_nlines, seg_npages;
    int      seg_cache_idx;
};

static const char *fmt_encname(rd_fmt_t f, const char *path)
{
    if (f == RD_FMT_TXT) {
        rdtxt_info info;
        if (rdtxt_probe(path, &info) == 0) {
            switch (info.enc) {
                case RD_ENC_UTF8: return "UTF-8";
                case RD_ENC_UTF16LE: return "UTF-16LE";
                case RD_ENC_UTF16BE: return "UTF-16BE";
                case RD_ENC_GB18030: return "GB18030";
                case RD_ENC_BIG5: return "Big5(按GB18030)";
                case RD_ENC_ASCII: return "ASCII";
            }
        }
    }
    return "";
}

static int book_meas(uint32_t cp, int fs, int *adv, void *ctx)
{
    (void)fs;
    rd_book *b = (rd_book *)ctx;
    return rdft_advance(b->ft, cp, adv);
}

/* ---- 文本：建索引（逐段 layout） ---- */
static int build_index(rd_book *b)
{
    rd_src_reset(b->src);
    size_t cap_segs = 64, cap_pages = 1024;
    b->segs = (seg_t *)malloc(cap_segs * sizeof(seg_t));
    b->pages = (rd_book_page *)malloc(cap_pages * sizeof(rd_book_page));
    if (!b->segs || !b->pages) return -6;
    b->nsegs = b->npages = 0;

    uint8_t *utf8 = (uint8_t *)malloc(RDTXT_SEG_UTF8_MAX + 8);
    if (!utf8) return -6;

    int seg_idx = 0;
    size_t ulen = 0;
    while (rd_src_next(b->src, utf8, RDTXT_SEG_UTF8_MAX + 8, &ulen) == 0) {
        if (seg_idx >= (int)cap_segs) { cap_segs *= 2; b->segs = (seg_t *)realloc(b->segs, cap_segs * sizeof(seg_t)); }
        uint32_t *cps = NULL; size_t n = 0;
        rd_utf8_to_cp(utf8, ulen, &cps, &n);
        rd_layout_in in;
        rd_layout_out out;
        rd_line *lines = (rd_line *)malloc((n ? n : 1) * sizeof(rd_line));
        rd_page *pages = (rd_page *)malloc((n ? n : 1) * sizeof(rd_page));
        if (!lines || !pages) { free(lines); free(pages); free(cps); free(utf8); return -6; }
        in.chars = cps; in.n = (int32_t)n; in.fs = b->fs; in.line_scale = b->ls;
        in.page_w = b->content_w; in.page_h = b->content_h; in.indent = b->fs;
        in.meas = book_meas; in.mctx = b;
        out.lines = lines; out.pages = pages; out.max_lines = (int)(n ? n : 1); out.max_pages = (int)(n ? n : 1);
        int lrc = rd_layout(&in, &out);
        free(cps);
        if (lrc != RD_LAYOUT_OK) { free(lines); free(pages); break; }
        b->segs[seg_idx].page_start = b->npages;
        b->segs[seg_idx].page_count = out.npages;
        for (int p = 0; p < out.npages; p++) {
            if (b->npages >= (int)cap_pages) { cap_pages *= 2; b->pages = (rd_book_page *)realloc(b->pages, cap_pages * sizeof(rd_book_page)); }
            b->pages[b->npages].seg = seg_idx;
            b->pages[b->npages].seg_char = out.pages[p].first_char;
            b->npages++;
        }
        free(lines); free(pages);
        seg_idx++;
    }
    free(utf8);
    b->nsegs = seg_idx;
    return 0;
}

/* ---- 正文重显 + 布局到复用缓冲 ---- */
static int load_seg(rd_book *b, int seg_idx)
{
    if (seg_idx == b->seg_cache_idx) return 0;
    size_t cap = RDTXT_SEG_UTF8_MAX + 8;
    if (!b->seg_utf8) b->seg_utf8 = (uint8_t *)malloc(cap);
    if (!b->seg_utf8) return -6;
    size_t ulen = 0;
    if (rd_src_seg(b->src, seg_idx, b->seg_utf8, cap, &ulen) != 0) return -4;
    size_t n = 0;
    free(b->seg_cps); b->seg_cps = NULL;
    if (rd_utf8_to_cp(b->seg_utf8, ulen, &b->seg_cps, &n) != RD_ENC_OK) return -5;
    b->seg_cps_n = n;
    if (b->seg_lines) free(b->seg_lines);
    if (b->seg_pages) free(b->seg_pages);
    b->seg_lines = (rd_line *)malloc((n ? n : 1) * sizeof(rd_line));
    b->seg_pages = (rd_page *)malloc((n ? n : 1) * sizeof(rd_page));
    if (!b->seg_lines || !b->seg_pages) return -6;
    rd_layout_in in;
    rd_layout_out out;
    in.chars = b->seg_cps; in.n = (int32_t)n; in.fs = b->fs; in.line_scale = b->ls;
    in.page_w = b->content_w; in.page_h = b->content_h; in.indent = b->fs;
    in.meas = book_meas; in.mctx = b;
    out.lines = b->seg_lines; out.pages = b->seg_pages; out.max_lines = (int)(n ? n : 1); out.max_pages = (int)(n ? n : 1);
    int lrc = rd_layout(&in, &out);
    if (lrc != RD_LAYOUT_OK) { b->seg_nlines = b->seg_npages = 0; b->seg_cache_idx = -1; return -4; }
    b->seg_nlines = out.nlines; b->seg_npages = out.npages;
    b->seg_cache_idx = seg_idx;
    return 0;
}

int rd_book_open(rd_book **b, const char *path, const char *font_path,
                 int fs, int ls, int pw, int ph, int mx, int my, int top)
{
    if (!b || !path) return -1;
    rd_book *x = (rd_book *)calloc(1, sizeof *x);
    if (!x) return -6;
    if (strlen(path) >= sizeof x->path) { free(x); return -2; }
    strcpy(x->path, path);
    if (font_path) { if (strlen(font_path) >= sizeof x->font) { free(x); return -2; } strcpy(x->font, font_path); }
    const char *sl = strrchr(path, '/');
    strncpy(x->base, sl ? sl + 1 : path, sizeof x->base - 1); x->base[sizeof x->base - 1] = 0;
    char *dot = strrchr(x->base, '.'); if (dot) *dot = 0;

    if (fs <= 0) fs = 20;
    if (ls <= 0) ls = 130;
    x->fs = fs; x->ls = ls; x->pw = pw; x->ph = ph; x->mx = mx; x->my = my; x->top = top;
    x->content_w = pw - 2 * mx;
    x->content_h = ph - top - my;
    if (x->content_w < 10 || x->content_h < 10) { goto close; }

    if (rd_src_open(&x->src, path) != 0) goto close;
    x->fmt = rd_src_fmt(x->src);
    x->encname = fmt_encname(x->fmt, path);
    x->is_img = (x->fmt == RD_FMT_CBZ);

    if (!x->is_img) {
        if (rdft_init(&x->ft) != 0) goto close;
        if (font_path && rdft_load_font(x->ft, x->font) != 0) { rdft_free(x->ft); x->ft = NULL; goto close; }
        if (x->ft) rdft_set_px(x->ft, fs);
        x->seg_cache_idx = -1;
        if (build_index(x) != 0) goto close;
    } else {
        int pages = rd_src_pages(x->src);
        x->npages = pages > 0 ? pages : 0;
    }
    x->cur = 0;
    *b = x;
    return 0;
close:
    rd_book_close(x);
    return -1;
}

void rd_book_close(rd_book *b)
{
    if (!b) return;
    free(b->segs);
    free(b->pages);
    free(b->seg_utf8);
    free(b->seg_cps);
    free(b->seg_lines);
    free(b->seg_pages);
    if (b->ft) rdft_free(b->ft);
    if (b->src) rd_src_free(b->src);
    free(b);
}

int rd_book_pages(rd_book *b) { return b ? b->npages : 0; }
int rd_book_current(rd_book *b) { return b ? b->cur : 0; }
int rd_book_font(rd_book *b)   { return b ? b->fs : 0; }
int rd_book_ls(rd_book *b)     { return b ? b->ls : 0; }
int rd_book_is_image(rd_book *b) { return b ? b->is_img : 0; }
const char *rd_book_encname(const rd_book *b) { return b ? (b->encname ? b->encname : "") : ""; }

void rd_book_geom(rd_book *b, int *fs, int *ls, int *pw, int *ph, int *mx, int *my, int *top)
{
    if (!b) return;
    if (fs) *fs = b->fs;
    if (ls) *ls = b->ls;
    if (pw) *pw = b->pw;
    if (ph) *ph = b->ph;
    if (mx) *mx = b->mx;
    if (my) *my = b->my;
    if (top) *top = b->top;
}
const char *rd_book_basename(const rd_book *b) { return b ? b->base : ""; }
const char *rd_book_path(const rd_book *b)     { return b ? b->path : ""; }

void rd_book_anchor(rd_book *b, int *seg, int32_t *ch)
{
    if (!b || b->npages <= 0) { if (seg) *seg = 0; if (ch) *ch = 0; return; }
    int p = b->cur < 0 ? 0 : (b->cur >= b->npages ? b->npages - 1 : b->cur);
    if (seg) *seg = b->pages[p].seg;
    if (ch) *ch = b->pages[p].seg_char;
}

int rd_book_turn(rd_book *b, int delta)
{
    if (!b || b->npages <= 0) return 0;
    int np = b->cur + delta;
    if (np < 0) np = 0;
    if (np >= b->npages) np = b->npages - 1;
    b->cur = np;
    return np;
}

/* ---- 文本页渲染（FreeType 字形 → 全屏 565） ---- */
static int render_text_page(rd_book *b, int page_no, uint16_t *out, int pitch, uint16_t bg565, uint16_t fg565)
{
    int npix = b->pw * b->ph;
    for (int i = 0; i < npix; i++) out[i] = bg565;
    rd_book_page *pg = &b->pages[page_no];
    int seg_idx = (int)pg->seg;
    if (seg_idx < 0 || seg_idx >= b->nsegs) return -1;
    if (load_seg(b, seg_idx) != 0) return -2;
    int local_page = page_no - b->segs[seg_idx].page_start;
    if (local_page < 0 || local_page >= b->seg_npages) return 1;
    rd_page *pp = &b->seg_pages[local_page];
    int asc = rdft_ascender(b->ft);
    int screen_x0 = b->mx;
    int screen_y0 = b->top;
    for (int li = 0; li < pp->nlines; li++) {
        rd_line *ln = &b->seg_lines[pp->first_line + li];
        int pen = screen_x0 + ln->x;
        int baseline = screen_y0 + ln->y + asc;
        for (int32_t ci = ln->s; ci < ln->e; ci++) {
            uint32_t cp = b->seg_cps[ci];
            int adv = 0, bw = 0, bh = 0, left = 0, btop = 0;
            const uint8_t *bmp = NULL;
            rdft_glyph(b->ft, cp, &adv, &bmp, &bw, &bh, &left, &btop);
            if (bmp && bw > 0)
                rdft_blend565(out, pitch, b->pw, b->ph, pen, baseline, bmp, bw, bh, left, btop, fg565, bg565);
            pen += adv;
        }
    }
    return 0;
}

/* ---- CBZ 图片页渲染（rdimg 解码+降采样 → 内容区居中） ---- */
static int render_img_page(rd_book *b, int page_no, uint16_t *out, int pitch, uint16_t bg565)
{
    int npix = b->pw * b->ph;
    for (int i = 0; i < npix; i++) out[i] = bg565;
    uint8_t *data = NULL; size_t size = 0;
    if (rd_src_page(b->src, page_no, &data, &size) != 0) return -1;
    uint16_t *scaled = NULL; int sw = 0, sh = 0;
    if (rdimg_decode_scale(data, size, b->content_w, b->content_h, &scaled, &sw, &sh) != 0) {
        free(data); return -2;
    }
    int x0 = b->mx + (b->content_w - sw) / 2;
    int y0 = b->top + (b->content_h - sh) / 2;
    int pitch_px = pitch / 2;
    for (int y = 0; y < sh; y++) {
        int ty = y0 + y; if (ty < 0 || ty >= b->ph) continue;
        for (int x = 0; x < sw; x++) {
            int tx = x0 + x; if (tx < 0 || tx >= b->pw) continue;
            out[(size_t)ty * pitch_px + tx] = scaled[(size_t)y * sw + x];
        }
    }
    free(scaled);
    free(data);
    return 0;
}

int rd_book_render(rd_book *b, int page_no, uint16_t *out, int pitch, uint16_t bg565, uint16_t fg565)
{
    if (!b || !out || b->npages <= 0 || page_no < 0 || page_no >= b->npages) return -1;
    if (b->is_img) return render_img_page(b, page_no, out, pitch, bg565);
    return render_text_page(b, page_no, out, pitch, bg565, fg565);
}

/* ---- 重排 + 回锚 ---- */
int rd_book_set_size(rd_book *b, int fs, int ls)
{
    if (!b) return -1;
    if (b->is_img) { b->fs = fs; b->ls = ls; return 0; }
    if (fs <= 0) fs = b->fs;
    if (ls <= 0) ls = b->ls;
    int anchor_seg, anchor_ch;
    rd_book_anchor(b, &anchor_seg, &anchor_ch);
    return rd_book_jump_to_anchor(b, anchor_seg, anchor_ch, fs, ls);
}

int rd_book_jump_to_anchor(rd_book *b, int seg, int32_t ch, int fs, int ls)
{
    if (!b) return -1;
    if (b->is_img) {
        if (seg >= 0 && seg < b->npages) b->cur = seg;
        return b->cur;
    }
    if (fs != b->fs || ls != b->ls) {
        b->fs = fs; b->ls = ls;
        b->content_w = b->pw - 2 * b->mx;
        b->content_h = b->ph - b->top - b->my;
        if (b->ft) rdft_set_px(b->ft, fs);
        seg_t *nos = b->segs; int n_oldsegs = b->nsegs;
        rd_book_page *nop = b->pages; int n_oldpages = b->npages;
        b->segs = NULL; b->pages = NULL; b->nsegs = b->npages = 0;
        if (build_index(b) != 0) { b->segs = nos; b->pages = nop; b->nsegs = n_oldsegs; b->npages = n_oldpages; return -5; }
        free(nos); free(nop);
    }
    int target = 0;
    for (int p = 0; p < b->npages; p++) {
        int ps = b->pages[p].seg;
        if (ps < seg) { target = p + 1; continue; }
        if (ps > seg) break;
        if (b->pages[p].seg_char >= ch) { target = p; break; }
        target = p;
    }
    if (target >= b->npages) target = b->npages - 1;
    if (target < 0) target = 0;
    b->cur = target;
    return target;
}

/* ---- SDK 字库兜底（文本格式） ---- */
int rd_book_render_text(rd_book *b, int page_no, rd_book_line_fn fn, void *ctx)
{
    if (!b || !fn || b->is_img || b->npages <= 0 || page_no < 0 || page_no >= b->npages) return -1;
    rd_book_page *pg = &b->pages[page_no];
    int seg_idx = (int)pg->seg;
    if (seg_idx < 0 || seg_idx >= b->nsegs) return -1;
    if (load_seg(b, seg_idx) != 0) return -2;
    int local_page = page_no - b->segs[seg_idx].page_start;
    if (local_page < 0 || local_page >= b->seg_npages) return 1;
    rd_page *pp = &b->seg_pages[local_page];
    uint8_t *line_utf8 = (uint8_t *)malloc((size_t)(b->content_w * 4 + 32));
    if (!line_utf8) return -6;
    for (int li = 0; li < pp->nlines; li++) {
        rd_line *ln = &b->seg_lines[pp->first_line + li];
        int x = b->mx + ln->x, y = b->top + ln->y;
        size_t o = 0;
        for (int32_t ci = ln->s; ci < ln->e; ci++) {
            uint8_t tmp[4];
            int n = rd_cp_to_utf8(b->seg_cps[ci], tmp);
            memcpy(line_utf8 + o, tmp, (size_t)n); o += (size_t)n;
        }
        line_utf8[o] = 0;
        fn(x, y, (const char *)line_utf8, (int)o, ctx);
    }
    free(line_utf8);
    return 0;
}

/* ---- 目录（转 rd_src） ---- */
int rd_book_toc_n(const rd_book *b)
{
    return (b && b->src && !b->is_img) ? rd_src_toc_n(b->src) : 0;
}
int rd_book_toc(const rd_book *b, int i, char *title, int tsz, int *seg, int32_t *ch)
{
    if (!b || !b->src || b->is_img || !title) return -1;
    rd_toc_entry t;
    if (rd_src_toc(b->src, i, &t) != 0) return -1;
    strncpy(title, t.title, (size_t)tsz - 1); title[tsz - 1] = 0;
    if (seg) *seg = t.seg;
    if (ch) *ch = t.ch;
    return 0;
}