/* app/book.c — 书桥实现（见 app/book.h）。 */
#include "book.h"
#include "rdtxt.h"
#include "rdlayout.h"
#include "../engine/rdft.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct seg {
    size_t  file_off, file_len;
    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];    /* 文件名 */
    const char     *encname;
    rdft          *ft;
    rd_enc_t       enc;

    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 */
    int cur;            /* 当前页 */

    /* 当前渲染段的复用缓冲 */
    uint8_t  *seg_utf8;  size_t seg_utf8_cap;
    uint32_t *seg_cps;   size_t seg_cps_n, seg_cps_cap;
    /* 当前段布局 */
    rd_line *seg_lines;  rd_page *seg_pages; int seg_nlines, seg_npages;
    int     seg_cache_idx;   /* 当前缓冲对应段；-1=无 */
};

static const char *encname_of(rd_enc_t e)
{
    switch (e) {
        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 "?";
}

/* 测量回调：排版器逐字测 advance → rdft_advance（不栅格化）。 */
static int book_meas(uint32_t cp, int fs, int *adv, void *ctx)
{
    (void)fs;
    rd_book *b = (rd_book *)ctx;
    /* advance 受字号影响：rdft 已 set_px(fs)，故用当前 rdft 度量即可 */
    return rdft_advance(b->ft, cp, adv);
}

static int build_index(rd_book *b)
{
    int rc = 0;
    rdtxt_reader *r = NULL;
    if (rdtxt_reader_open(b->path, &(rdtxt_info){ .enc = b->enc, .file_size = 0, .path = "" },
                          &r) != 0) return -1;
    /* rdtxt_reader_open 以 info 的 enc 为准（path 域不读） */
    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) { rd_book_close(b); return -6; }
    b->nsegs = b->npages = 0;

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

    size_t off = 0, flen = 0, ulen = 0;
    int seg_idx = 0;
    while (rdtxt_reader_next(r, utf8, RDTXT_SEG_UTF8_MAX + 8, &ulen, &off, &flen) == 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_utf8_to_cp 内部 malloc */
        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); rd_book_close(b); 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);
        /* 布局容量不足时翻倍重试（罕见）。 */
        int lrc = rd_layout(&in, &out);
        free(cps);
        if (lrc != RD_LAYOUT_OK) { free(lines); free(pages); break; }   /* 段为空/异常：跳过 */
        /* 登记段 + 页 */
        b->segs[seg_idx].file_off = off;
        b->segs[seg_idx].file_len = flen;
        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);
    rdtxt_reader_free(r);
    b->nsegs = seg_idx;
    rc = 0;
    return rc;
}

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); }
    /* 文件名 */
    const char *sl = strrchr(path, '/');
    strncpy(x->base, sl ? sl + 1 : path, sizeof x->base - 1); x->base[sizeof x->base - 1] = 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) { close: free(x); return -3; }

    rdtxt_info info;
    if (rdtxt_probe(path, &info) != 0) goto close;
    x->enc = info.enc;
    x->encname = encname_of(info.enc);

    if (rdft_init(&x->ft) != 0) goto close;
    if (font_path && rdft_load_font(x->ft, x->font) != 0) { rdft_free(x->ft); goto close; }
    if (x->ft) rdft_set_px(x->ft, fs);

    x->seg_cache_idx = -1;
    if (build_index(x) != 0) { rd_book_close(x); return -5; }
    x->cur = 0;
    *b = x;
    return 0;
}

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);
    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; }
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_encname(const rd_book *b)  { return b ? b->encname : ""; }
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;
}

/* --- 读回一段并布局到复用缓冲（渲染用）--- */
static int load_seg(rd_book *b, int seg_idx)
{
    if (seg_idx == b->seg_cache_idx) return 0;
    seg_t *s = &b->segs[seg_idx];
    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 (rdtxt_convert_span(b->path, b->enc, s->file_off, s->file_len, b->seg_utf8, cap, &ulen) != RD_ENC_OK)
        return -4;
    size_t n = 0;
    free(b->seg_cps);                     /* rd_utf8_to_cp 内部 malloc 新数组 */
    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;
    /* 布局（容量：段码点数为上界） */
    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_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;
    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;   /* 空页 */
    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, top = 0;
            const uint8_t *bmp = NULL;
            rdft_glyph(b->ft, cp, &adv, &bmp, &bw, &bh, &left, &top);
            if (bmp && bw > 0)
                rdft_blend565(out, pitch, b->pw, b->ph, pen, baseline, bmp, bw, bh, left, top, fg565, bg565);
            pen += adv;
            if (cp == '\t') pen += adv;   /* 制表符已由布局按空格 advance 计量，此处保持游标 */
        }
    }
    return 0;
}

/* 重排 + 回锚：以 (seg,ch) 为锚重排全书；返回重排后的页（0=成功，负值=错误）。 */
int rd_book_set_size(rd_book *b, int fs, int ls)
{
    if (!b) return -1;
    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 (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);
        /* 重建索引 */
        seg_t *nos = b->segs; int n_old_segs = b->nsegs;
        rd_book_page *nop = b->pages; int n_old_pages = 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_old_segs; b->npages = n_old_pages;
            return -5;
        }
        free(nos); free(nop);
    }
    /* 回锚：找第一个 (seg==anchorSeg && seg_char>=anchorCh) 的页，或段内第一个 seg_char>=ch；跨段按 seg 序 */
    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：逐行回调正文文本（无 TTF/OTF 时用 meow_ui_text 渲染）。 */
int rd_book_render_text(rd_book *b, int page_no, rd_book_line_fn fn, void *ctx)
{
    if (!b || !fn || 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];
    /* 单线程渲染：每行最多 content_w 个单宽字符 → ≤4B/字 UTF-8 */
    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;
        /* 组 utf8 */
        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;
}