#!/usr/bin/env python3
"""Create and validate bounded, fail-closed evidence manifests."""
from __future__ import annotations
import argparse, datetime as dt, hashlib, json, math, os, platform, re, shutil, subprocess, sys, tempfile, time
from pathlib import Path

HEX40 = re.compile(r"^[0-9a-f]{40}$")
HEX64 = re.compile(r"^[0-9a-f]{64}$")
ID = re.compile(r"^[A-Za-z][A-Za-z0-9_.-]{0,127}$")
ISO = re.compile(r"^\d{4}-\d\d-\d\dT\d\d:\d\d:\d\d(?:\.\d+)?Z$")
SAFE_ENV = ("os", "kernel", "architecture", "python", "uv")
SECRET_PATTERNS = [
    re.compile(r"(?:cookie|set-cookie|authorization|proxy-authorization|x-api-key|api-key|x-auth-token)\s*:", re.I),
    re.compile(r"\bbearer\s+[^\s]+", re.I),
    re.compile(r"-----BEGIN [^-]*PRIVATE KEY-----", re.I),
    re.compile(r"\b(?:password|passwd|secret|token)\s*[:=]", re.I),
    re.compile(r"(?:^|\s)--?(?:password|passwd|secret|token)(?:\s+|=)\S+", re.I),
]
SAFE_CHILD_ENV = ("PATH", "HOME", "TMPDIR", "TMP", "TEMP", "LANG", "LC_ALL", "VIRTUAL_ENV", "UV_CACHE_DIR")
SHELL_NAMES = {"sh", "bash", "dash", "zsh", "ksh", "fish", "cmd", "cmd.exe", "powershell", "powershell.exe", "pwsh", "pwsh.exe"}


def die(msg):
    print(str(msg), file=sys.stderr); return 2


def git(root: Path, *args, check=True):
    p = subprocess.run(["git", f"-c", f"safe.directory={root}", *args], cwd=root, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    if check and p.returncode: raise ValueError(p.stderr.decode("utf-8", "replace").strip() or "git failed")
    return p


def inside(root, value, *, allow_absolute=False):
    if not isinstance(value, str) or not value or (Path(value).is_absolute() and not allow_absolute):
        raise ValueError("paths must be nonempty repository-relative paths")
    p = Path(value)
    if ".." in p.parts: raise ValueError("path traversal is forbidden")
    if p.parts and p.parts[0] == ".git": raise ValueError(".git paths are forbidden")
    candidate = (root / p).resolve()
    try: candidate.relative_to(root.resolve())
    except ValueError: raise ValueError(f"path outside repository: {value}")
    if (root / p).is_symlink() and not candidate.is_relative_to(root.resolve()): raise ValueError("symlink escapes repository")
    return candidate, candidate.relative_to(root.resolve()).as_posix()


def utc_now(): return dt.datetime.now(dt.timezone.utc).isoformat().replace("+00:00", "Z")
def canonical(obj): return json.dumps(obj, sort_keys=True, separators=(",", ":"), ensure_ascii=False) + "\n"
def text_bytes(b): return b.decode("utf-8", "replace")


def scan_sensitive(text, secrets, forbidden):
    for s in secrets:
        if s and s in text: return "secret value"
    for pattern in SECRET_PATTERNS + forbidden:
        if pattern.search(text): return f"forbidden pattern: {pattern.pattern}"
    return None


def validate_regexes(values):
    if not isinstance(values, list) or any(not isinstance(x, str) for x in values): raise ValueError("forbidden_regexes must be strings")
    try: return [re.compile(x) for x in values]
    except re.error as e: raise ValueError(f"invalid forbidden regex: {e}")


def validate_argv(argv):
    if not isinstance(argv,list) or not argv or any(not isinstance(x,str) for x in argv): raise ValueError("commands require nonempty argv string arrays")
    executable=Path(argv[0]).name.lower()
    if executable in SHELL_NAMES or any(x.lower() in ("shell", "shell=true") for x in argv): raise ValueError("shell commands are forbidden")


def run_bounded(argv, root, env, max_bytes):
    proc=subprocess.Popen(argv,cwd=root,stdout=subprocess.PIPE,stderr=subprocess.STDOUT,shell=False,env=env,bufsize=0)
    stream=proc.stdout
    if stream is None: raise ValueError("command output pipe unavailable")
    data=bytearray()
    try:
        while True:
            chunk=stream.read(min(65536,max_bytes-len(data)+1))
            if not chunk: break
            data.extend(chunk)
            if len(data)>max_bytes:
                proc.kill(); proc.wait()
                raise ValueError("command output exceeds max_output_bytes")
        return proc.wait(),bytes(data)
    finally:
        stream.close()
        if proc.poll() is None:
            proc.kill(); proc.wait()


def status_paths(root):
    raw = git(root, "status", "--porcelain=v1", "-z").stdout
    out=[]
    for entry in raw.split(b"\0"):
        if not entry: continue
        path = entry[3:] if len(entry) >= 3 else b""
        if entry[:2] in (b"R ", b" R", b"R?"):
            path = path.split(b"\0",1)[-1]
        out.append(path.decode("utf-8", "surrogateescape"))
    return out


def check_clean(root, allowed):
    bad = [p for p in status_paths(root) if p not in allowed]
    if bad: raise ValueError("source tree is not clean: " + ", ".join(bad))


def plan_checks(plan, root):
    if not isinstance(plan, dict): raise ValueError("plan must be an object")
    for key in ("hash_paths", "commands", "limitations", "secret_env_names", "forbidden_regexes", "command_env_allowlist"):
        if key in plan and not isinstance(plan[key], list): raise ValueError(f"{key} must be a list")
    names = plan.get("secret_env_names", [])
    if any(not isinstance(n, str) for n in names): raise ValueError("secret_env_names must be strings")
    secrets = [os.environ.get(n, "") for n in names if os.environ.get(n, "")]
    forbidden = validate_regexes(plan.get("forbidden_regexes", []))
    requested = plan.get("environment", list(SAFE_ENV[:4]))
    if not isinstance(requested, list) or len(set(requested)) != len(requested) or any(x not in SAFE_ENV for x in requested): raise ValueError("invalid environment allowlist")
    child_names=plan.get("command_env_allowlist",list(SAFE_CHILD_ENV))
    if any(not isinstance(x,str) or not x or x not in SAFE_CHILD_ENV for x in child_names): raise ValueError("command_env_allowlist may contain only safe operational names")
    child_names=list(dict.fromkeys([*child_names,*names]))
    hash_paths=plan.get("hash_paths",[])
    if not hash_paths or any(not isinstance(x,str) or not x for x in hash_paths): raise ValueError("hash_paths must be a nonempty string list")
    command_plans=plan.get("commands",[])
    if not command_plans: raise ValueError("commands must be nonempty")
    seen=set(); command_ids=set(); commands=[]
    for index,spec in enumerate(command_plans):
        if not isinstance(spec, dict): raise ValueError("command must be object")
        argv=spec.get("argv"); validate_argv(argv)
        expected=spec.get("expected_exit_code",0); maxb=spec.get("max_output_bytes",65536)
        if not isinstance(expected,int) or isinstance(expected,bool) or not isinstance(maxb,int) or maxb < 0: raise ValueError("invalid command bounds")
        claims=spec.get("claims",[])
        if not isinstance(claims,list) or not claims or any(not isinstance(x,str) or not ID.fullmatch(x) for x in claims): raise ValueError("claims must be a nonempty list of valid IDs")
        if any(x in seen for x in claims): raise ValueError("duplicate claim ID")
        command_id=spec.get("id",f"command-{index}"); purpose=spec.get("purpose","")
        if not isinstance(command_id,str) or not ID.fullmatch(command_id) or command_id in command_ids: raise ValueError("invalid or duplicate command ID")
        if not isinstance(purpose,str): raise ValueError("command purpose must be a string")
        command_ids.add(command_id); seen.update(claims); commands.append((spec,argv,expected,maxb,claims))
    return secrets, forbidden, requested, child_names, commands


def tracked_blob(root, source, rel):
    info=git(root,"ls-tree",source,"--",rel).stdout.decode("utf-8","replace").strip().split()
    if len(info)<3 or info[1] not in ("blob",) or info[0] not in ("100644","100755"): raise ValueError(f"hash path is not tracked regular file: {rel}")
    oid=info[2]; blob=git(root,"cat-file","blob",oid).stdout
    return oid, hashlib.sha256(blob).hexdigest()


def atomic_write(path, data):
    if not path.parent.is_dir(): raise ValueError("output parent must already exist")
    fd,tmp=tempfile.mkstemp(prefix="."+path.name+".", dir=path.parent)
    try:
        with os.fdopen(fd,"w",encoding="utf-8",newline="") as f:
            f.write(data); f.flush(); os.fsync(f.fileno())
        os.replace(tmp,path)
        dir_fd = os.open(path.parent, os.O_RDONLY)
        try: os.fsync(dir_fd)
        finally: os.close(dir_fd)
    finally:
        try: os.unlink(tmp)
        except FileNotFoundError: pass


def run(args):
    root=Path(args.repo_root).resolve(); plan_path,plan_rel=inside(root,args.plan); out,out_rel=inside(root,args.output)
    if plan_path.suffix.lower()!=".json": raise ValueError("plan must be a JSON file")
    if not out.parent.is_dir(): raise ValueError("output parent must already exist")
    plan_bytes=plan_path.read_bytes(); plan_sha256=hashlib.sha256(plan_bytes).hexdigest()
    plan=json.loads(plan_bytes.decode("utf-8")); secrets,forbidden,env_keys,child_names,commandspec=plan_checks(plan,root)
    for _,argv,_,_,_ in commandspec:
        violation=scan_sensitive("\n".join(argv),secrets,forbidden)
        if violation: raise ValueError("sensitive command rejected before execution: "+violation)
    check_clean(root,{plan_rel,out_rel})
    source=git(root,"rev-parse","HEAD").stdout.decode().strip()
    if not HEX40.fullmatch(source): raise ValueError("source revision is not full SHA")
    files=[]
    for item in plan.get("hash_paths",[]):
        path,rel=inside(root,item)
        if not path.is_file() or path.is_symlink(): raise ValueError(f"hash path is not a regular file: {item}")
        oid,sha=tracked_blob(root,source,rel)
        if hashlib.sha256(path.read_bytes()).hexdigest()!=sha: raise ValueError(f"source hash mismatch: {rel}")
        files.append({"path":rel,"sha256":sha,"blob_oid":oid})
    bound_paths={record["path"] for record in files}
    if plan_rel==out_rel or plan_rel in bound_paths or out_rel in bound_paths: raise ValueError("plan/output paths must not overlap bound source paths")
    child_env={name:os.environ[name] for name in child_names if name in os.environ}
    result_commands=[]; claim_map={}
    for i,(spec,argv,expected,maxb,claim_ids) in enumerate(commandspec):
        started=utc_now(); t=time.monotonic(); returncode,raw=run_bounded(argv,root,child_env,maxb); finished=utc_now()
        output=text_bytes(raw); violation=scan_sensitive("\n".join(argv)+"\n"+output,secrets,forbidden)
        if violation: raise ValueError("sensitive evidence rejected: "+violation)
        c={"id":spec.get("id",f"command-{i}"),"purpose":spec.get("purpose",""),"argv":argv,"exit_code":returncode,"expected_exit_code":expected,"max_output_bytes":maxb,"output":output,"started_at_utc":started,"finished_at_utc":finished,"duration_seconds":time.monotonic()-t,"claim_ids":claim_ids}
        result_commands.append(c)
        for cid in claim_ids:
            claim_map[cid]=[
                f"/commands/{i}/argv",
                f"/commands/{i}/exit_code",
                f"/commands/{i}/expected_exit_code",
                f"/commands/{i}/output",
                f"/commands/{i}/started_at_utc",
                f"/commands/{i}/finished_at_utc",
            ]
    env={k:None for k in env_keys}
    if "os" in env: env["os"]=platform.system()
    if "kernel" in env: env["kernel"]=platform.release()
    if "architecture" in env: env["architecture"]=platform.machine()
    if "python" in env: env["python"]=platform.python_version()
    if "uv" in env:
        p=subprocess.run(["uv","--version"],stdout=subprocess.PIPE,stderr=subprocess.PIPE) if shutil.which("uv") else None
        env["uv"]=text_bytes((p.stdout+p.stderr).strip()) if p and p.returncode==0 else None
    # Commands are evidence producers, not trusted source mutators. Recheck the
    # tree and every bound blob before persisting their claims.
    check_clean(root,{plan_rel,out_rel})
    if git(root,"rev-parse","HEAD").stdout.decode().strip()!=source: raise ValueError("HEAD changed during verification")
    if not plan_path.is_file() or hashlib.sha256(plan_path.read_bytes()).hexdigest()!=plan_sha256: raise ValueError("plan changed during verification")
    for record in files:
        if hashlib.sha256((root/record["path"]).read_bytes()).hexdigest()!=record["sha256"]:
            raise ValueError(f"source changed during verification: {record['path']}")
    success=all(c["exit_code"]==c["expected_exit_code"] for c in result_commands)
    manifest={"schema":"evidence-manifest/v1","source_revision":source,"source_tree_clean":True,"excluded_paths":[plan_rel,out_rel],"plan":{"path":plan_rel,"sha256":plan_sha256},"generated_at":utc_now(),"environment":env,"commands":result_commands,"files":files,"claims":claim_map,"redaction":{"checked":True,"violations":[]},"limitations":plan.get("limitations",[]),"result":"success" if success else "failure"}
    atomic_write(out,canonical(manifest))
    return 0 if success else 1


def pointer(obj,ptr):
    if not isinstance(ptr,str) or not ptr.startswith("/"): raise ValueError("invalid claim pointer")
    cur=obj
    for part in ptr[1:].split("/"):
        part=part.replace("~1","/").replace("~0","~")
        if isinstance(cur,list) and part.isdigit() and int(part)<len(cur): cur=cur[int(part)]
        elif isinstance(cur,dict) and part in cur: cur=cur[part]
        else: raise ValueError("claim pointer does not resolve")
    return cur


def validate(args):
    root=Path(args.repo_root).resolve(); mp,mp_rel=inside(root,args.manifest); raw=mp.read_text(encoding="utf-8"); obj=json.loads(raw)
    if canonical(obj)!=raw: raise ValueError("manifest is not canonical JSON")
    required={"schema","source_revision","source_tree_clean","excluded_paths","plan","generated_at","commands","files","claims","redaction","environment","limitations","result"}
    if set(obj)!=required or obj["schema"]!="evidence-manifest/v1" or obj["result"] not in ("success","failure"): raise ValueError("invalid manifest structure")
    if obj["source_tree_clean"] is not True or not isinstance(obj["excluded_paths"],list): raise ValueError("source tree was not clean")
    if not isinstance(obj["generated_at"],str) or not ISO.fullmatch(obj["generated_at"]): raise ValueError("invalid generated timestamp")
    if len(obj["excluded_paths"])!=2 or len(set(obj["excluded_paths"]))!=2 or any(not isinstance(x,str) for x in obj["excluded_paths"]) or obj["excluded_paths"][1]!=mp_rel: raise ValueError("invalid excluded paths")
    for excluded in obj["excluded_paths"]: inside(root,excluded)
    if not isinstance(obj["plan"],dict) or set(obj["plan"])!={"path","sha256"} or obj["plan"]["path"]!=obj["excluded_paths"][0] or not isinstance(obj["plan"]["sha256"],str) or not HEX64.fullmatch(obj["plan"]["sha256"]): raise ValueError("invalid plan binding")
    plan_path,plan_rel=inside(root,obj["plan"]["path"])
    if plan_path.suffix.lower()!=".json" or not plan_path.is_file() or plan_path.is_symlink(): raise ValueError("bound plan is unavailable")
    plan_bytes=plan_path.read_bytes()
    if hashlib.sha256(plan_bytes).hexdigest()!=obj["plan"]["sha256"]: raise ValueError("plan hash mismatch")
    plan=json.loads(plan_bytes.decode("utf-8")); plan_secrets,plan_forbidden,requested_env,_,planned_commands=plan_checks(plan,root)
    check_clean(root,set(obj["excluded_paths"]))
    src=obj["source_revision"]
    if not isinstance(src,str) or not HEX40.fullmatch(src): raise ValueError("invalid source revision")
    if git(root,"cat-file","-e",src,check=False).returncode: raise ValueError("missing source revision")
    head=git(root,"rev-parse","HEAD").stdout.decode().strip()
    if git(root,"merge-base","--is-ancestor",src,head,check=False).returncode: raise ValueError("source is not ancestor")
    if not isinstance(obj["environment"],dict) or not obj["environment"] or any(not isinstance(k,str) or k not in SAFE_ENV or not (isinstance(v,str) or v is None) for k,v in obj["environment"].items()): raise ValueError("invalid environment")
    if set(obj["environment"])!=set(requested_env): raise ValueError("environment does not match plan")
    if not isinstance(obj["limitations"],list) or any(not isinstance(x,str) for x in obj["limitations"]) or obj["limitations"]!=plan.get("limitations",[]): raise ValueError("invalid limitations")
    if obj["redaction"]!={"checked":True,"violations":[]}: raise ValueError("redaction failed")
    if not isinstance(obj["claims"],dict) or any(
        not isinstance(k,str) or not ID.fullmatch(k) or not isinstance(v,list)
        or len(v)!=6 or any(not isinstance(ptr,str) for ptr in v)
        for k,v in obj["claims"].items()
    ): raise ValueError("invalid claims")
    if not isinstance(obj["files"],list) or not obj["files"]: raise ValueError("files must be nonempty")
    planned_paths=[inside(root,item)[1] for item in plan.get("hash_paths",[])]
    if [f.get("path") if isinstance(f,dict) else None for f in obj["files"]]!=planned_paths: raise ValueError("file records do not match plan")
    claim_seen=set()
    for f in obj["files"]:
        if not isinstance(f,dict) or set(f)!={"path","sha256","blob_oid"}: raise ValueError("invalid file record")
        _,rel=inside(root,f["path"]); path=root/rel
        if not HEX64.fullmatch(f["sha256"]) or not HEX40.fullmatch(f["blob_oid"]): raise ValueError("invalid file identity")
        oid,sha=tracked_blob(root,src,rel)
        if oid!=f["blob_oid"] or sha!=f["sha256"] or hashlib.sha256(path.read_bytes()).hexdigest()!=sha: raise ValueError("file hash mismatch")
    if any(f["path"] in set(obj["excluded_paths"]) for f in obj["files"]): raise ValueError("evidence paths overlap bound source paths")
    if not isinstance(obj["commands"],list) or not obj["commands"] or len(obj["commands"])!=len(planned_commands): raise ValueError("commands do not match plan")
    command_ids=set()
    for i,c in enumerate(obj["commands"]):
        spec,planned_argv,planned_exit,planned_max,planned_claims=planned_commands[i]
        command_keys={"id","purpose","argv","exit_code","expected_exit_code","max_output_bytes","output","started_at_utc","finished_at_utc","duration_seconds","claim_ids"}
        if not isinstance(c,dict) or set(c)!=command_keys: raise ValueError("invalid command structure")
        if not isinstance(c["id"],str) or not ID.fullmatch(c["id"]) or c["id"] in command_ids or not isinstance(c["purpose"],str): raise ValueError("invalid command identity")
        command_ids.add(c["id"])
        validate_argv(c["argv"])
        if not isinstance(c["output"],str): raise ValueError("invalid command types")
        if any(not isinstance(c[k],int) or isinstance(c[k],bool) for k in ("exit_code","expected_exit_code","max_output_bytes")) or c["max_output_bytes"]<0 or len(c["output"].encode())>c["max_output_bytes"]: raise ValueError("invalid command bounds")
        if not isinstance(c["duration_seconds"],(int,float)) or isinstance(c["duration_seconds"],bool) or not math.isfinite(c["duration_seconds"]) or c["duration_seconds"]<0: raise ValueError("invalid command duration")
        if not isinstance(c["claim_ids"],list) or any(not isinstance(x,str) or not ID.fullmatch(x) for x in c["claim_ids"]): raise ValueError("invalid command fields")
        if c["id"]!=spec.get("id",f"command-{i}") or c["purpose"]!=spec.get("purpose","") or c["argv"]!=planned_argv or c["expected_exit_code"]!=planned_exit or c["max_output_bytes"]!=planned_max or c["claim_ids"]!=planned_claims: raise ValueError("command record does not match plan")
        if not ISO.fullmatch(c["started_at_utc"]) or not ISO.fullmatch(c["finished_at_utc"]): raise ValueError("invalid timestamp")
        for cid in c["claim_ids"]:
            if cid in claim_seen or cid not in obj["claims"]: raise ValueError("duplicate or missing claim")
            claim_seen.add(cid)
            pointers=obj["claims"][cid]
            expected_pointers=[
                f"/commands/{i}/argv",
                f"/commands/{i}/exit_code",
                f"/commands/{i}/expected_exit_code",
                f"/commands/{i}/output",
                f"/commands/{i}/started_at_utc",
                f"/commands/{i}/finished_at_utc",
            ]
            if pointers!=expected_pointers: raise ValueError("claim pointers are not canonical")
            for ptr in pointers: pointer(obj,ptr)
        violation=scan_sensitive("\n".join(c["argv"])+"\n"+c["output"],plan_secrets,plan_forbidden)
        if violation: raise ValueError("redaction violation")
    if claim_seen != set(obj["claims"]): raise ValueError("unreferenced claim")
    expected="success" if all(c["exit_code"]==c["expected_exit_code"] for c in obj["commands"]) else "failure"
    if obj["result"]!=expected: raise ValueError("result inconsistent")
    return 0


def main():
    p=argparse.ArgumentParser(); sub=p.add_subparsers(dest="op",required=True)
    r=sub.add_parser("run"); r.add_argument("--repo-root",required=True); r.add_argument("--plan",required=True); r.add_argument("--output",required=True)
    v=sub.add_parser("validate"); v.add_argument("--repo-root",required=True); v.add_argument("--manifest",required=True)
    a=p.parse_args()
    try: return run(a) if a.op=="run" else validate(a)
    except (OSError, ValueError, TypeError, KeyError, AttributeError, UnicodeError, json.JSONDecodeError, re.error, subprocess.SubprocessError) as e: return die(e)
if __name__=="__main__": sys.exit(main())