"""Post-run analysis: turn a session directory into a symbol-annotated report.

The report is the "complete map" half of the deliverable: hits by function,
watch hits, memory writes, coverage and snapshot inventory, ready for
offline comparison between runs (bare-metal vs VFIO, old firmware vs new).
"""
from __future__ import annotations

import json
import os
import re
from collections import Counter, defaultdict

from .record import load_events, load_meta

_TRACE_KINDS = ("exec", "access", "read", "write")
_ACCESS_RE = re.compile(
    r"Invalid (read|write) at addr (0x[0-9a-fA-F]+), size (\d+), region '([^']*)', reason: (\w+)"
)
_INTERRUPT_RE = re.compile(
    r"riscv_cpu_do_interrupt: hart:(\d+), async:(\d+), cause:([0-9a-fA-F]+), "
    r"epc:(0x[0-9a-fA-F]+), tval:(0x[0-9a-fA-F]+), desc=([\w_]+)"
)


def parse_qemu_faults(log_text: str) -> list[dict]:
    """Parse QEMU ``-d guest_errors,unimp,int`` logs into fault records.

    Each record pairs the most recent invalid access (if any) with the
    exception it raised, which is exactly the "first divergence" report a
    firmware probe needs.
    """
    faults: list[dict] = []
    pending_access: dict | None = None
    for line in log_text.splitlines():
        access = _ACCESS_RE.search(line)
        if access:
            pending_access = {
                "rw": access.group(1),
                "access_addr": int(access.group(2), 16),
                "size": int(access.group(3)),
                "region": access.group(4),
                "reason": access.group(5),
            }
            continue
        interrupt = _INTERRUPT_RE.search(line)
        if interrupt:
            faults.append(
                {
                    "hart": int(interrupt.group(1)),
                    "async": int(interrupt.group(2)),
                    "cause": int(interrupt.group(3), 16),
                    "epc": int(interrupt.group(4), 16),
                    "tval": int(interrupt.group(5), 16),
                    "desc": interrupt.group(6),
                    "access": pending_access,
                }
            )
            pending_access = None
    return faults


_RISCV_CAUSES = {
    0: "instruction address misaligned",
    1: "instruction access fault",
    2: "illegal instruction",
    3: "breakpoint",
    4: "load address misaligned",
    5: "load access fault",
    6: "store address misaligned",
    7: "store access fault",
}


def describe_fault(fault: dict, bias: int = 0) -> str:
    epc = fault["epc"]
    fw_pc = epc - bias
    cause = fault["cause"]
    desc = _RISCV_CAUSES.get(cause & 0xFF, fault.get("desc", "exception"))
    lines = [
        f"first exception: {fault.get('desc', '?')} (cause {cause:#x}: {desc})",
        f"  epc:      {epc:#x}" + (f"  (firmware vaddr {fw_pc:#x})" if bias else ""),
        f"  tval:     {fault.get('tval', 0):#x}",
    ]
    access = fault.get("access")
    if access:
        lines.insert(
            1,
            f"  access:   {access['rw']} at {access['access_addr']:#x} "
            f"({access['size']} bytes, reason={access['reason']})",
        )
    return "\n".join(lines)


def _trace_kind(record: dict) -> str | None:
    """Native/TCG trace records use ``t``; folded session events use ``type``."""
    return record.get("type") or record.get("t")


def _number(value, default: int = 0) -> int:
    if isinstance(value, int):
        return value
    if isinstance(value, str):
        try:
            return int(value, 0)
        except ValueError:
            return default
    return default


def load_trace(session_dir: str, meta: dict | None = None) -> list[dict]:
    """Load the trace blob referenced by ``meta['trace_blob']`` (R4)."""
    meta = meta if meta is not None else load_meta(session_dir)
    rel = meta.get("trace_blob")
    if not rel:
        return []
    path = rel if os.path.isabs(rel) else os.path.join(session_dir, rel)
    records: list[dict] = []
    try:
        with open(path, "r", encoding="utf-8") as fh:
            for line in fh:
                line = line.strip()
                if not line:
                    continue
                record = json.loads(line)
                if _trace_kind(record) != "summary":
                    records.append(record)
    except (OSError, ValueError):
        return []
    return records


def render_summary(session_dir: str, symbols=None, max_rows: int = 40) -> str:
    meta = load_meta(session_dir)
    events = load_events(session_dir)
    return render_summary_from(
        meta, events, symbols=symbols, max_rows=max_rows, trace=load_trace(session_dir, meta)
    )


def render_summary_from(meta: dict, events: list[dict], symbols=None, max_rows: int = 40,
                        trace: list[dict] | None = None) -> str:
    if trace is None:
        trace = [e for e in events if _trace_kind(e) in _TRACE_KINDS]
    lines: list[str] = []
    lines.append(f"# green-eye session summary: {meta.get('name', '?')}")
    lines.append("")
    lines.append(f"* format: `{meta.get('format', '?')}`  green-eye {meta.get('greeneye', '?')}")
    lines.append(f"* directory: `{meta.get('dir', '.')}`")
    lines.append(f"* events: {len(events)}")
    counts = Counter(event.get("type", "?") for event in events)
    lines.append("* event counts: " + ", ".join(f"{k}={v}" for k, v in sorted(counts.items())))
    counts_meta = meta.get("counts")
    if counts_meta:
        lines.append("* recorder counts: " + ", ".join(f"{k}={v}" for k, v in sorted(counts_meta.items())))
    lines.append("")

    # QEMU exception report (probe sessions)
    fault_count = meta.get("qemu_fault_count")
    first = meta.get("qemu_first_fault")
    if fault_count or first:
        lines.append("## QEMU exceptions")
        lines.append("")
        lines.append(f"* total exceptions: {fault_count if fault_count is not None else '?'}")
        if meta.get("qemu_log_blob"):
            lines.append(f"* qemu log blob: `{meta['qemu_log_blob']}`")
        if first:
            access = first.get("access") or {}
            lines.append("")
            lines.append("| field | value |")
            lines.append("|---|---|")
            lines.append(f"| descriptor | `{first.get('desc', '?')}` |")
            lines.append(f"| cause | `{first.get('cause', 0):#x}` ({_RISCV_CAUSES.get(first.get('cause', 0) & 0xFF, '?')}) |")
            epc = first.get("epc", 0)
            bias = meta.get("bias") or 0
            epc_cell = f"`{epc:#x}`" + (f" (firmware vaddr `{epc - bias:#x}`)" if bias else "")
            lines.append(f"| epc | {epc_cell} |")
            lines.append(f"| tval | `{first.get('tval', 0):#x}` |")
            if access:
                lines.append(
                    f"| first access | `{access.get('rw')}` at `{access.get('access_addr', 0):#x}` "
                    f"({access.get('size')} bytes, reason `{access.get('reason')}`) |"
                )
            lines.append("")

    def annotate(addr):
        if not isinstance(addr, int):
            return ""
        if symbols is not None:
            return symbols.annotate(addr)
        return f"{addr:#x}"

    # Breakpoint hits
    bp_hits = [e for e in events if e.get("type") == "bp_hit"]
    if bp_hits:
        by_site: Counter = Counter()
        by_symbol: Counter = Counter()
        for event in bp_hits:
            key = event.get("symbol") or f"{event.get('pc', 0):#x}"
            by_site[(event.get("pc"), key)] += 1
            by_symbol[key] += 1
        lines.append("## Breakpoint hits")
        lines.append("")
        lines.append("| hits | pc | symbol |")
        lines.append("|---:|---|---|")
        for (pc, key), count in by_site.most_common(max_rows):
            lines.append(f"| {count} | `{pc:#x}` | `{key}` |")
        lines.append("")

    # Watchpoint hits
    watch_hits = [e for e in events if e.get("type") == "watch_hit"]
    if watch_hits:
        by_addr: Counter = Counter()
        for event in watch_hits:
            by_addr[(event.get("addr"), event.get("kind"))] += 1
        lines.append("## Watchpoint hits")
        lines.append("")
        lines.append("| hits | address | kind | symbol |")
        lines.append("|---:|---|---|---|")
        for (addr, kind), count in by_addr.most_common(max_rows):
            sym = symbols.resolve(addr) if symbols else None
            lines.append(f"| {count} | `{addr:#x}` | {kind} | `{sym.name if sym else ''}` |")
        lines.append("")

    # Memory writes
    writes = [e for e in events if e.get("type") == "mem_write"]
    if writes:
        regions = Counter()
        for event in writes:
            regions[(event.get("addr", 0) >> 12) << 12] += 1
        lines.append("## Memory writes")
        lines.append("")
        lines.append(f"* writes: {len(writes)}, distinct 4 KiB pages: {len(regions)}")
        lines.append("")
        lines.append("| page | writes | symbol |")
        lines.append("|---|---:|---|")
        for page, count in regions.most_common(max_rows):
            sym = symbols.resolve(page) if symbols else None
            lines.append(f"| `{page:#x}` | {count} | `{sym.name if sym else ''}` |")
        lines.append("")

    # Execution/access trace coverage (native R4 or folded TCG trace)
    if trace:
        def access_kind(record):
            kind = _trace_kind(record)
            if kind == "access":
                return "write" if str(record.get("rw", "")).startswith("w") else "read"
            return kind

        execs = [r for r in trace if access_kind(r) == "exec"]
        reads = [r for r in trace if access_kind(r) == "read"]
        writes = [r for r in trace if access_kind(r) == "write"]
        lines.append("## Execution trace")
        lines.append("")
        blob = meta.get("trace_blob")
        if blob:
            lines.append(f"* trace blob: `{blob}`")
        pcs = Counter()
        for record in execs:
            pcs[_number(record.get("pc"))] += 1
        suffix = f", unique PCs: {len(pcs)}" if execs else " (exec=off)"
        lines.append(f"* exec events: {len(execs)}{suffix}")
        read_pages = Counter()
        for record in reads:
            read_pages[(_number(record.get("addr")) >> 12) << 12] += 1
        write_pages = Counter()
        for record in writes:
            write_pages[(_number(record.get("addr")) >> 12) << 12] += 1
        lines.append(
            f"* accesses: {len(reads)} reads ({len(read_pages)} pages), "
            f"{len(writes)} writes ({len(write_pages)} pages)"
        )
        config = meta.get("trace") or {}
        if config:
            bits = [f"exec={'on' if config.get('exec') else 'off'}"]
            for key in ("start", "end"):
                if config.get(key) is not None:
                    bits.append(f"{key}={config[key]:#x}" if isinstance(config[key], int) else f"{key}={config[key]}")
            if config.get("max_events"):
                bits.append(f"max_events={config['max_events']}")
            if config.get("dropped"):
                bits.append(f"dropped={config['dropped']}")
            lines.append("* trace config: " + ", ".join(bits))
        lines.append("")

        if execs:
            by_sym = defaultdict(lambda: [0, 0])  # unique PCs, exec count
            for pc, count in pcs.items():
                sym = symbols.resolve(pc) if symbols else None
                entry = by_sym[sym.name if sym else f"{pc:#x}"]
                entry[0] += 1
                entry[1] += count
            lines.append("### Unique PCs by symbol")
            lines.append("")
            lines.append("| unique PCs | execs | symbol |")
            lines.append("|---:|---:|---|")
            for name, (unique, count) in sorted(by_sym.items(), key=lambda kv: -kv[1][1])[:max_rows]:
                lines.append(f"| {unique} | {count} | `{name}` |")
            lines.append("")

        if read_pages or write_pages:
            lines.append("### Accessed pages")
            lines.append("")
            lines.append("| page | reads | writes | symbol |")
            lines.append("|---|---:|---:|---|")
            for page in sorted(set(read_pages) | set(write_pages),
                               key=lambda p: -(read_pages.get(p, 0) + write_pages.get(p, 0)))[:max_rows]:
                sym = symbols.resolve(page) if symbols else None
                lines.append(
                    f"| `{page:#x}` | {read_pages.get(page, 0)} | {write_pages.get(page, 0)} "
                    f"| `{sym.name if sym else ''}` |"
                )
            lines.append("")

    # Coverage
    steps = [e for e in events if e.get("type") == "step"]
    if steps:
        pcs = {(e.get("pc")) for e in steps}
        lines.append("## Stepped coverage")
        lines.append("")
        lines.append(f"* steps: {len(steps)}, unique PCs: {len(pcs)}")
        by_sym = Counter()
        for pc in pcs:
            sym = symbols.resolve(pc) if symbols else None
            by_sym[sym.name if sym else f"{pc:#x}"] += 1
        lines.append("")
        lines.append("| PCs | symbol |")
        lines.append("|---:|---|")
        for name, count in by_sym.most_common(max_rows):
            lines.append(f"| {count} | `{name}` |")
        lines.append("")

    # Snapshots
    snapshots = meta.get("snapshots") or [e for e in events if e.get("type") == "snapshot_saved"]
    if snapshots:
        lines.append("## Snapshots")
        lines.append("")
        lines.append("| label | address | size | path | sha256 |")
        lines.append("|---|---|---:|---|---|")
        for snap in snapshots[:max_rows]:
            lines.append(
                f"| {snap.get('label')} | `{snap.get('addr', 0):#x}` | {snap.get('size', 0)} | "
                f"`{snap.get('path')}` | `{(snap.get('sha256') or '')[:16]}` |"
            )
        lines.append("")

    # Timeline excerpt
    notable = [e for e in events if e.get("type") in ("bp_hit", "leave", "watch_hit", "mem_write", "note", "exit")]
    if notable:
        lines.append("## Timeline (first hits)")
        lines.append("")
        for event in notable[:max_rows]:
            t = event.get("t", 0)
            kind = event.get("type")
            if kind in ("bp_hit", "leave"):
                site = event.get("symbol") or f"{event.get('pc', 0):#x}"
                extra = ""
                regs = event.get("regs") or {}
                if "a0" in regs:
                    extra = f" a0={regs['a0']:#x}"
                if kind == "leave" and "retval" in event:
                    extra += f" -> {event['retval']:#x}"
                lines.append(f"* `{t:8.3f}s` {kind}: {site}{extra}")
            elif kind == "watch_hit":
                lines.append(f"* `{t:8.3f}s` watch: {annotate(event.get('addr'))} ({event.get('kind')})")
            elif kind == "mem_write":
                lines.append(
                    f"* `{t:8.3f}s` write: {annotate(event.get('addr'))} "
                    f"{event.get('size')}B {event.get('data', '')[:32]}"
                )
            elif kind == "note":
                lines.append(f"* `{t:8.3f}s` note: {event.get('text')}")
            elif kind == "exit":
                lines.append(f"* `{t:8.3f}s` exit status={event.get('status')}")
        lines.append("")

    # Symbol-annotation table for automation
    lines.append("## Annotated sites")
    lines.append("")
    sites = Counter()
    for event in events:
        for key in ("pc", "addr"):
            value = event.get(key)
            if isinstance(value, int) and value and event.get("type") in ("bp_hit", "watch_hit", "mem_write"):
                sites[value] += 1
    lines.append("| address | count | annotation |")
    lines.append("|---|---:|---|")
    for addr, count in sites.most_common(max_rows):
        lines.append(f"| `{addr:#x}` | {count} | `{annotate(addr)}` |")
    lines.append("")
    return "\n".join(lines) + "\n"


def compare_sessions(a_dir: str, b_dir: str, symbols=None, max_rows: int = 40) -> str:
    """Diff two recorded sessions at the symbolic event level (A/B tooling)."""
    a_meta, b_meta = load_meta(a_dir), load_meta(b_dir)
    a_events, b_events = load_events(a_dir), load_events(b_dir)
    a_trace, b_trace = load_trace(a_dir, a_meta), load_trace(b_dir, b_meta)
    lines = [f"# green-eye session comparison", "", f"* A: {a_meta.get('name')} ({a_dir})", f"* B: {b_meta.get('name')} ({b_dir})", ""]

    def trace_kind(record: dict) -> str:
        kind = _trace_kind(record)
        if kind == "access":
            return "write" if str(record.get("rw", "")).startswith("w") else "read"
        return kind

    def profile(events, trace):
        bp = Counter()
        watch = Counter()
        writes = Counter()
        for event in events:
            if event.get("type") == "bp_hit":
                bp[event.get("symbol") or f"{event.get('pc', 0):#x}"] += 1
            elif event.get("type") == "watch_hit":
                watch[(event.get("addr"), event.get("kind"))] += 1
            elif event.get("type") == "mem_write":
                writes[(event.get("addr", 0) >> 12) << 12] += 1
        for record in trace:
            if trace_kind(record) == "write":
                writes[(_number(record.get("addr")) >> 12) << 12] += 1
        return bp, watch, writes

    a_bp, a_watch, a_writes = profile(a_events, a_trace)
    b_bp, b_watch, b_writes = profile(b_events, b_trace)

    lines.append("## Breakpoint profile delta (A vs B)")
    lines.append("")
    lines.append("| symbol | A hits | B hits | delta |")
    lines.append("|---|---:|---:|---:|")
    for name in sorted(set(a_bp) | set(b_bp), key=lambda k: -(a_bp.get(k, 0) + b_bp.get(k, 0)))[:max_rows]:
        lines.append(f"| `{name}` | {a_bp.get(name, 0)} | {b_bp.get(name, 0)} | {b_bp.get(name, 0) - a_bp.get(name, 0):+d} |")
    lines.append("")

    lines.append("## Watchpoint delta")
    lines.append("")
    lines.append("| address | kind | A | B |")
    lines.append("|---|---|---:|---:|")
    for key in sorted(set(a_watch) | set(b_watch), key=lambda k: -(a_watch.get(k, 0) + b_watch.get(k, 0)))[:max_rows]:
        lines.append(f"| `{key[0]:#x}` | {key[1]} | {a_watch.get(key, 0)} | {b_watch.get(key, 0)} |")
    lines.append("")

    lines.append("## Written pages delta")
    lines.append("")
    lines.append("| page | A writes | B writes |")
    lines.append("|---|---:|---:|")
    for page in sorted(set(a_writes) | set(b_writes), key=lambda k: -(a_writes.get(k, 0) + b_writes.get(k, 0)))[:max_rows]:
        lines.append(f"| `{page:#x}` | {a_writes.get(page, 0)} | {b_writes.get(page, 0)} |")
    lines.append("")

    def trace_totals(trace):
        totals = Counter()
        for record in trace:
            kind = trace_kind(record)
            if kind in ("exec", "read", "write"):
                totals[kind] += 1
        return totals

    a_totals, b_totals = trace_totals(a_trace), trace_totals(b_trace)
    if a_trace or b_trace:
        lines.append("## Trace stream totals (A vs B)")
        lines.append("")
        lines.append("| stream | A | B | delta |")
        lines.append("|---|---:|---:|---:|")
        for kind in ("exec", "read", "write"):
            a_count, b_count = a_totals.get(kind, 0), b_totals.get(kind, 0)
            lines.append(f"| {kind} | {a_count} | {b_count} | {b_count - a_count:+d} |")
        lines.append("")
    return "\n".join(lines) + "\n"