"""Task-scoped Git checkpoints owned by the coordinator, never by the model."""
from pathlib import Path
import subprocess


class TaskCommits:
    def __init__(self, root, enabled=True):
        if not isinstance(enabled, bool):
            raise ValueError('git_commits must be a JSON boolean')
        self.root = Path(root).resolve()
        self.enabled = enabled

    def git(self, *args):
        result = subprocess.run(['git', '-C', str(self.root), *args],
                                capture_output=True, timeout=60)
        if result.returncode:
            # Do not leak hooks, environment, signing details or credentials into reports.
            raise ValueError('Git ' + args[0] + ' failed; inspect Git configuration/hooks locally; changes preserved')
        return result.stdout.decode('utf-8', errors='surrogateescape')

    def changes(self):
        # Disable rename folding so each source/deletion is staged explicitly.
        raw = self.git('status', '--porcelain=v1', '-z', '--untracked-files=all', '--no-renames')
        return [row[3:] for row in raw.split('\0') if row]

    def preflight(self):
        if not self.enabled:
            return None
        self.repo = Path(self.git('rev-parse', '--show-toplevel').strip()).resolve()
        head = self.git('rev-parse', '--verify', 'HEAD').strip()
        self.git('symbolic-ref', '--quiet', 'HEAD')
        self.git('var', 'GIT_AUTHOR_IDENT')
        self.git('var', 'GIT_COMMITTER_IDENT')
        if self.changes():
            raise ValueError('Git working tree/index must be clean before each agent; commit or separately preserve existing changes first')
        return head

    def message(self, item, agent, row, result):
        task_id = item['id']
        if row['status'] in {'review', 'done', 'todo'} and not result.get('resolution_task'):
            path = self.root / 'state/commit_messages' / (agent + '.txt')
            if path.is_symlink() or not path.resolve().is_relative_to(self.root) or not path.is_file():
                raise ValueError('Missing task commit message: state/commit_messages/' + agent + '.txt')
            text = path.read_text(encoding='utf-8').strip()
            lines = text.splitlines()
            if (not lines or not 15 <= len(lines[0]) <= 100 or
                    not lines[0][0].isascii() or not lines[0][0].isupper() or
                    any(ord(c) < 32 for c in text if c != '\n') or
                    len(text) > 12000 or len(lines) < 4 or lines[1] != '' or
                    'Changes:' not in text or 'Validation:' not in text or
                    len('\n'.join(lines[2:])) < 40):
                raise ValueError('Commit message needs a concrete English subject (15..100 chars), blank line, Changes: and Validation: with actual results')
        else:
            # An interrupted model cannot be relied on to write a completion message.
            # Preserve its bounded partial work explicitly as incomplete before remediation.
            reason = row.get('reason') or str(result)
            text = ('Record blocked task and remediation handoff\n\n'
                    'Changes: Preserve incomplete work and blocker metadata for ' + task_id +
                    '. This checkpoint does not mark implementation accepted.\n'
                    'Validation: Session ended with status ' + row['status'] + '.\n'
                    'Blocker: ' + reason)
        return task_id + ': ' + text + '\n\nTask: ' + task_id + '\nAgent: ' + agent + \
            '\nRole: ' + item['role'] + '\nAction: ' + item['action'] + '\nStatus: ' + row['status'] + '\n'

    def commit(self, item, agent, row, result, expected_head, task_title):
        if not self.enabled:
            return None
        if self.git('rev-parse', 'HEAD').strip() != expected_head:
            raise ValueError('Agent changed Git HEAD; coordinator will not commit or continue automatically')
        paths = self.changes()
        for name in paths:
            if not (self.repo / name).is_relative_to(self.root):
                raise ValueError('Changes outside project root; refusing to include unrelated files in task commit')
        message = self.message(item, agent, row, result) + '\nTask title: ' + task_title + '\n'
        if not paths:
            raise ValueError('Task transition produced no Git changes; refusing an empty task commit')
        self.git('add', '--', *[':(top,literal)' + name for name in paths])
        # Include only the explicitly enumerated project files; never git add . / -A.
        staged = self.git('diff', '--cached', '--no-relative', '--name-only', '-z').split('\0')
        if any(name and name not in paths for name in staged):
            raise ValueError('Unexpected staged files; changes preserved for inspection')
        message_path = self.root / 'state/runs' / agent / 'commit-message.txt'
        message_path.parent.mkdir(parents=True, exist_ok=True)
        message_path.write_text(message, encoding='utf-8')
        self.git('commit', '--file', str(message_path))
        commit = self.git('rev-parse', 'HEAD').strip()
        if self.changes():
            raise ValueError('Git hook or concurrent writer left changes after commit; inspect before next agent')
        return commit