// Step 1926: LanguageSeamFrameDetector
// Finds language boundary frames in a decoded polyglot stack.
//
//  t1: detectSeams returns indices of boundary frames
//  t2: primarySeam returns first seam index, -1 if none
//  t3: seamCount counts boundary frames
//  t4: frameLanguages returns unique langs in order of appearance
//  t5: crossesBoundary detects specific language transitions

#include "LanguageSeamFrameDetector.h"
#include "PolyglotStackTraceDecoder.h"
#include <iostream>

namespace ws = whetstone;

static int p=0,f=0;
#define T(n) { std::cout<<"  "<<#n<<"... "; }
#define P() { std::cout<<"PASS\n"; ++p; }
#define F(m) { std::cout<<"FAIL: "<<m<<"\n"; ++f; }
#define C(c,m) if(!(c)){F(m);return;}

// Build a poly-sort stack: Python frames calling into Rust
static std::vector<ws::StackFrame> makePolySortStack() {
    ws::PolyglotStackTraceDecoder dec;
    return dec.decode({
        {1, "run",        "main.py",    10},
        {2, "generate",   "datagen.py", 20},
        {3, "sort_array", "sort.rs",    5},
        {4, "partition",  "sort.rs",    30},
    });
}

void t1(){
    T(detectSeams_returns_boundary_indices);
    ws::LanguageSeamFrameDetector det;
    auto frames = makePolySortStack();
    auto seams = det.detectSeams(frames);
    // generate(1) and sort_array(2) are at the boundary
    C(seams.size() == 2, "two seam frames");
    C(seams[0] == 1, "index 1 (generate)");
    C(seams[1] == 2, "index 2 (sort_array)");
    P();
}

void t2(){
    T(primarySeam_first_index_or_minus1);
    ws::LanguageSeamFrameDetector det;
    auto frames = makePolySortStack();
    C(det.primarySeam(frames) == 1, "primary seam at index 1");
    // all-same-language: no seam
    ws::PolyglotStackTraceDecoder dec;
    auto mono = dec.decode({{1,"a","a.py",1},{2,"b","b.py",2}});
    C(det.primarySeam(mono) == -1, "no seam returns -1");
    P();
}

void t3(){
    T(seamCount);
    ws::LanguageSeamFrameDetector det;
    auto frames = makePolySortStack();
    C(det.seamCount(frames) == 2, "two seam frames");
    ws::PolyglotStackTraceDecoder dec;
    auto mono = dec.decode({{1,"a","a.rs",1},{2,"b","b.rs",2}});
    C(det.seamCount(mono) == 0, "zero seams in mono stack");
    P();
}

void t4(){
    T(frameLanguages_unique_ordered);
    ws::LanguageSeamFrameDetector det;
    auto frames = makePolySortStack();
    auto langs = det.frameLanguages(frames);
    C(langs.size() == 2,         "two languages");
    C(langs[0] == "Python",      "Python first");
    C(langs[1] == "Rust",        "Rust second");
    // three-language stack
    ws::PolyglotStackTraceDecoder dec;
    auto tri = dec.decode({
        {1,"a","a.py",1}, {2,"b","b.rs",1}, {3,"c","c.go",1}
    });
    auto tl = det.frameLanguages(tri);
    C(tl.size() == 3,    "three languages");
    C(tl[0] == "Python", "Python");
    C(tl[1] == "Rust",   "Rust");
    C(tl[2] == "Go",     "Go");
    P();
}

void t5(){
    T(crossesBoundary_specific_transitions);
    ws::LanguageSeamFrameDetector det;
    auto frames = makePolySortStack();
    C( det.crossesBoundary(frames,"Python","Rust"), "Python→Rust present");
    C(!det.crossesBoundary(frames,"Rust","Python"), "Rust→Python not present");
    C(!det.crossesBoundary(frames,"Python","Go"),   "Python→Go not present");
    // reversed stack would have Rust→Python
    ws::PolyglotStackTraceDecoder dec;
    auto rev = dec.decode({
        {1,"partition","sort.rs",1},
        {2,"sort_array","sort.rs",1},
        {3,"generate","datagen.py",1},
        {4,"run","main.py",1},
    });
    C( det.crossesBoundary(rev,"Rust","Python"), "Rust→Python in reversed stack");
    P();
}

int main(){
    std::cout << "Step 1926: LanguageSeamFrameDetector\n";
    t1(); t2(); t3(); t4(); t5();
    std::cout << "\n" << p << "/" << (p+f) << " passed\n";
    return f > 0 ? 1 : 0;
}