#!/usr/bin/env bash
set -euo pipefail

# ─── Mosaic Framework Installer ──────────────────────────────────────────────
#
# Installs/upgrades the framework DATA to ~/.config/mosaic/.
# No executables are placed on PATH — the mosaic npm CLI is the only binary.
#
# Called by tools/install.sh (the unified installer). Can also be run directly.
#
# Environment:
#   MOSAIC_HOME              — target directory (default: ~/.config/mosaic)
#   MOSAIC_INSTALL_MODE      — prompt|keep|overwrite (default: prompt)
#   MOSAIC_ALLOW_MISSING_SEQUENTIAL_THINKING — 1 to bypass MCP check
#   MOSAIC_SKIP_SKILLS_SYNC  — 1 to skip skill sync
# ──────────────────────────────────────────────────────────────────────────────

SOURCE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
TARGET_DIR="${MOSAIC_HOME:-$HOME/.config/mosaic}"
INSTALL_MODE="${MOSAIC_INSTALL_MODE:-prompt}"

# Shared framework path-ownership manifest reader (#791). Parity with
# packages/mosaic/src/framework/manifest.ts — both consume framework-manifest.txt.
# Sourcing does not run its CLI dispatch (guarded by BASH_SOURCE==$0).
# shellcheck source=tools/_lib/manifest.sh
source "$SOURCE_DIR/tools/_lib/manifest.sh"

# Which paths a keep-mode upgrade may touch is no longer a hand-maintained
# denylist. It is derived from the shared framework-manifest.txt (#791): the
# updater only ever creates/overwrites framework-owned paths and only prunes a
# retired framework file inside a shipped framework subtree. Everything else —
# every operator file, and every path the manifest never anticipated — is
# operator-owned by default (fail-safe) and is never written or deleted. See
# sync_framework_keep() below and packages/mosaic/src/framework/manifest.ts.

# Framework-owned contract files: re-copied from defaults/ on every upgrade (the
# user must not edit them; a divergent copy is backed up once before overwrite).
# USER_SEEDED files are written once on first install, then owned by the user.
# Both lists are APPEND-FRIENDLY — add a new shipped framework file here and to the
# matching list in packages/mosaic/src/config/file-adapter.ts.
FRAMEWORK_OWNED=("CONSTITUTION.md" "AGENTS.md" "STANDARDS.md")
USER_SEEDED=("TOOLS.md")

# Current framework schema version — bump this when the layout changes.
# The migration system uses this to run upgrade steps.
FRAMEWORK_VERSION=3

# ─── colours ──────────────────────────────────────────────────────────────────
if [[ -t 1 ]]; then
  GREEN='\033[0;32m' YELLOW='\033[0;33m' RED='\033[0;31m'
  CYAN='\033[0;36m' BOLD='\033[1m' RESET='\033[0m'
else
  GREEN='' YELLOW='' RED='' CYAN='' BOLD='' RESET=''
fi

ok()   { echo -e "  ${GREEN}✓${RESET} $1"; }
warn() { echo -e "  ${YELLOW}⚠${RESET} $1" >&2; }
fail() { echo -e "  ${RED}✗${RESET} $1" >&2; }
step() { echo -e "\n${BOLD}$1${RESET}"; }

# ─── snapshot / restore (crash safety for upgrades) ──────────────────────────
SNAPSHOT_DIR=""
make_snapshot() {
  is_existing_install || return 0
  SNAPSHOT_DIR="$(mktemp -d "${TMPDIR:-/tmp}/mosaic-snapshot-XXXXXX")"
  cp -a "$TARGET_DIR/." "$SNAPSHOT_DIR/" 2>/dev/null || true
}
restore_snapshot() {
  [[ -n "$SNAPSHOT_DIR" && -d "$SNAPSHOT_DIR" ]] || return 0
  fail "Install interrupted/failed — restoring previous state from snapshot"
  rm -rf "$TARGET_DIR"; mkdir -p "$TARGET_DIR"
  cp -a "$SNAPSHOT_DIR/." "$TARGET_DIR/" 2>/dev/null || true
}
cleanup_snapshot() { [[ -n "$SNAPSHOT_DIR" && -d "$SNAPSHOT_DIR" ]] && rm -rf "$SNAPSHOT_DIR"; SNAPSHOT_DIR=""; }

# Reconcile contract files after sync: framework-owned overwrite (backup-once),
# user-seeded seed-if-absent.
reconcile_framework_files() {
  local defaults="$TARGET_DIR/defaults" f
  [[ -d "$defaults" ]] || return 0
  for f in "${FRAMEWORK_OWNED[@]}"; do
    [[ -f "$defaults/$f" ]] || continue
    # Already current — skip to avoid mtime churn.
    if [[ -f "$TARGET_DIR/$f" ]] && cmp -s "$TARGET_DIR/$f" "$defaults/$f"; then
      continue
    fi
    if [[ -f "$TARGET_DIR/$f" && ! -f "$TARGET_DIR/${f}.pre-constitution.bak" ]]; then
      cp "$TARGET_DIR/$f" "$TARGET_DIR/${f}.pre-constitution.bak"
      warn "$f is now framework-owned and was updated; your previous copy is saved as ${f}.pre-constitution.bak — re-apply intended changes as a .local overlay or policy/ file (see CONSTITUTION.md / constitution/LAYER-MODEL.md)."
    fi
    cp "$defaults/$f" "$TARGET_DIR/$f"
  done
  for f in "${USER_SEEDED[@]}"; do
    [[ -f "$defaults/$f" ]] || continue
    if [[ ! -f "$TARGET_DIR/$f" ]]; then
      cp "$defaults/$f" "$TARGET_DIR/$f"
      ok "Seeded $f from defaults"
    fi
  done
}

# ─── helpers ──────────────────────────────────────────────────────────────────

is_existing_install() {
  [[ -d "$TARGET_DIR" ]] || return 1
  [[ -f "$TARGET_DIR/AGENTS.md" || -f "$TARGET_DIR/SOUL.md" ]]
}

installed_framework_version() {
  local vf="$TARGET_DIR/.framework-version"
  if [[ -f "$vf" ]]; then
    cat "$vf" 2>/dev/null || echo "0"
  else
    # No version file = legacy install (version 0 or 1)
    if [[ -d "$TARGET_DIR/bin" ]]; then
      echo "1"   # Has bin/ → pre-migration legacy
    else
      echo "0"   # Fresh or unknown
    fi
  fi
}

write_framework_version() {
  echo "$FRAMEWORK_VERSION" > "$TARGET_DIR/.framework-version"
}

select_install_mode() {
  case "$INSTALL_MODE" in
    keep|overwrite|prompt) ;;
    *)
      fail "Invalid MOSAIC_INSTALL_MODE='$INSTALL_MODE'. Use: prompt, keep, overwrite."
      exit 1
      ;;
  esac

  if ! is_existing_install; then
    INSTALL_MODE="overwrite"
    return
  fi

  case "$INSTALL_MODE" in
    keep|overwrite) ;;
    prompt)
      if [[ -t 0 ]]; then
        echo ""
        echo "Existing Mosaic install detected at: $TARGET_DIR"
        echo "  1) keep      Update framework, preserve local files (SOUL.md, USER.md, etc.)"
        echo "  2) overwrite Replace everything"
        echo "  3) cancel    Abort"
        printf "Selection [1/2/3] (default: 1): "
        read -r selection
        case "${selection:-1}" in
          1|k|K|keep) INSTALL_MODE="keep" ;;
          2|o|O|overwrite) INSTALL_MODE="overwrite" ;;
          *) fail "Install cancelled."; exit 1 ;;
        esac
      else
        INSTALL_MODE="keep"
      fi
      ;;
  esac
}

sync_framework() {
  local source_real target_real
  source_real="$(cd "$SOURCE_DIR" && pwd -P)"
  target_real="$(mkdir -p "$TARGET_DIR" && cd "$TARGET_DIR" && pwd -P)"

  if [[ "$source_real" == "$target_real" ]]; then
    warn "Source and target are the same directory; skipping file sync."
    return
  fi

  if [[ "$INSTALL_MODE" == "keep" ]]; then
    # The `mosaic update` path. Manifest-driven, never-deleting-outside-framework:
    # operator config is structurally protected (#791). No rsync --delete here.
    manifest_load
    sync_framework_keep
    return
  fi

  # overwrite mode — a full replace, chosen only for a fresh install or when the
  # operator explicitly asks to replace everything. No operator state to protect.
  sync_framework_overwrite
}

# Keep-mode sync: create/refresh framework-owned files and prune only retired
# framework files inside shipped framework subtrees. Operator-owned and unknown
# paths (fail-safe default) are never written and never deleted — the #791 HARD
# GATE. Single code path (no rsync) so it is byte-for-byte parity-testable.
sync_framework_keep() {
  local src="$SOURCE_DIR" dst="$TARGET_DIR" abs rel root

  # 1) Overlay copy — every framework-owned source file, refreshed only when its
  #    bytes changed (no mtime churn on unchanged files, never on operator files).
  while IFS= read -r -d '' abs; do
    rel="${abs#"$src"/}"
    case "$rel" in
      .git|.git/*|.framework-version|*.pre-constitution.bak) continue ;;
    esac
    manifest_is_framework "$rel" || continue
    if [[ -f "$dst/$rel" ]] && cmp -s "$abs" "$dst/$rel"; then continue; fi
    [[ "$rel" == */* ]] && mkdir -p "$dst/${rel%/*}"
    cp "$abs" "$dst/$rel"
  done < <(find "$src" -type f -print0)

  # 2) Scoped prune — within each shipped framework subtree root, remove
  #    framework-owned target files the current source no longer ships. Operator
  #    carve-outs (e.g. tools/_lib/credentials.json) resolve to operator and are
  #    skipped; unknown paths resolve to operator too — both are unreachable here.
  while IFS= read -r root; do
    [[ -n "$root" && -d "$dst/$root" ]] || continue
    while IFS= read -r -d '' abs; do
      rel="${abs#"$dst"/}"
      case "$rel" in *.pre-constitution.bak) continue ;; esac
      [[ -f "$src/$rel" ]] && continue                          # still shipped
      manifest_is_framework "$rel" || continue
      rm -f "$abs"
    done < <(find "$dst/$root" -type f -print0)
    # Drop framework dirs left empty by the prune (never touches a dir that still
    # holds an operator file — those are never emptied).
    find "$dst/$root" -type d -empty -delete 2>/dev/null || true
  done < <(manifest_subtree_roots)
}

# Overwrite-mode sync: full replace. Only reached for a fresh install or an
# explicit operator "replace everything" choice, so nothing is preserved.
sync_framework_overwrite() {
  if command -v rsync >/dev/null 2>&1; then
    rsync -a --delete \
      --exclude ".git" --exclude ".framework-version" --exclude "*.pre-constitution.bak" \
      "$SOURCE_DIR/" "$TARGET_DIR/"
    return
  fi
  find "$TARGET_DIR" -mindepth 1 -maxdepth 1 \
    ! -name ".git" ! -name ".framework-version" ! -name "*.pre-constitution.bak" \
    -exec rm -rf {} +
  cp -R "$SOURCE_DIR"/. "$TARGET_DIR"/
  rm -rf "$TARGET_DIR/.git"
}

# ═══════════════════════════════════════════════════════════════════════════════
# Migrations — run sequentially from the installed version to FRAMEWORK_VERSION
# ═══════════════════════════════════════════════════════════════════════════════

run_migrations() {
  local from_version
  from_version="$(installed_framework_version)"

  if [[ "$from_version" -ge "$FRAMEWORK_VERSION" ]]; then
    return  # Already current
  fi

  step "Running migrations (v${from_version} → v${FRAMEWORK_VERSION})"

  # ── Migration: v0/v1 → v2 ─────────────────────────────────────────────────
  # Remove bin/ directory — all executables now live in the npm CLI.
  # Scripts that were in bin/ are now in tools/_scripts/.
  if [[ "$from_version" -lt 2 ]]; then
    if [[ -d "$TARGET_DIR/bin" ]]; then
      ok "Removing legacy bin/ directory (executables now in npm CLI)"
      rm -rf "$TARGET_DIR/bin"
    fi

    # Remove old mosaic PATH entry from shell profiles
    for profile in "$HOME/.bashrc" "$HOME/.zshrc" "$HOME/.profile"; do
      if [[ -f "$profile" ]] && grep -qF "$TARGET_DIR/bin" "$profile"; then
        # Remove the PATH line and the comment above it
        sed -i.mosaic-migration-bak \
          -e "\|# Mosaic agent framework|d" \
          -e "\|$TARGET_DIR/bin|d" \
          "$profile"
        ok "Cleaned up old PATH entry from $(basename "$profile")"
        rm -f "${profile}.mosaic-migration-bak"
      fi
    done

    # Remove stale rails/ symlink
    if [[ -L "$TARGET_DIR/rails" ]]; then
      rm -f "$TARGET_DIR/rails"
    fi
  fi

  # ── Migration: v2 → v3 (Constitution split) ───────────────────────────────
  # CONSTITUTION.md / AGENTS.md / STANDARDS.md become framework-owned (overwritten
  # on upgrade). reconcile_framework_files() has already run before this point: it
  # backed up any user-edited copy to <file>.pre-constitution.bak and installed the
  # new framework version. Nothing further to do here — the advisory was emitted at
  # reconcile time. (STANDARDS.local.md composition lands with the overlay composer.)
  if [[ "$from_version" -lt 3 ]]; then
    ok "Migrated to the Constitution layout (framework-owned CONSTITUTION/AGENTS/STANDARDS)"
  fi
}

# ═══════════════════════════════════════════════════════════════════════════════
# Main
# ═══════════════════════════════════════════════════════════════════════════════

step "Installing Mosaic framework"

mkdir -p "$TARGET_DIR"
select_install_mode

if [[ "$INSTALL_MODE" == "keep" ]]; then
  ok "Install mode: keep local files (SOUL.md, USER.md, TOOLS.md, memory/)"
else
  ok "Install mode: overwrite"
fi

# Snapshot before any destructive file operation; restore on interrupt/failure.
make_snapshot
trap 'restore_snapshot' ERR INT TERM

sync_framework

# Ensure persistent directories exist
mkdir -p "$TARGET_DIR/memory"
mkdir -p "$TARGET_DIR/credentials"

# Reconcile contract files from defaults/ into the framework root: framework-owned
# files (CONSTITUTION/AGENTS/STANDARDS) are overwritten every upgrade (a divergent
# copy is backed up once); user-seeded files (TOOLS) are written on first install only.
#
# This list must match the framework-contract whitelist in
# packages/mosaic/src/config/file-adapter.ts (FileConfigAdapter.syncFramework).
# SOUL.md and USER.md are intentionally NOT seeded here — they are generated
# by `mosaic init` from templates with user-supplied values.
reconcile_framework_files

# Ensure tool scripts are executable
find "$TARGET_DIR/tools" -name "*.sh" -exec chmod +x {} + 2>/dev/null || true
find "$TARGET_DIR/tools/_scripts" -type f -exec chmod +x {} + 2>/dev/null || true

ok "Framework synced to $TARGET_DIR"

# Run migrations before post-install (migrations may remove old bin/ etc.)
run_migrations

# File-system phase complete and consistent — clear the restore trap.
trap - ERR INT TERM
cleanup_snapshot

# Testability / minimal-install hook: stop after the file-system phase, before any
# environment-touching post-install steps (runtime linking, MCP setup, skills, doctor).
if [[ "${MOSAIC_SYNC_ONLY:-0}" == "1" ]]; then
  write_framework_version
  ok "Sync-only mode: file phase complete"
  exit 0
fi

step "Post-install tasks"

SCRIPTS="$TARGET_DIR/tools/_scripts"

if [[ -x "$SCRIPTS/mosaic-link-runtime-assets" ]]; then
  if "$SCRIPTS/mosaic-link-runtime-assets" >/dev/null 2>&1; then
    ok "Runtime assets linked"
  else
    warn "Runtime asset linking failed (non-fatal)"
  fi
fi

if [[ -x "$SCRIPTS/mosaic-ensure-sequential-thinking" ]]; then
  if "$SCRIPTS/mosaic-ensure-sequential-thinking" >/dev/null 2>&1; then
    ok "sequential-thinking MCP configured"
  else
    if [[ "${MOSAIC_ALLOW_MISSING_SEQUENTIAL_THINKING:-0}" == "1" ]]; then
      warn "sequential-thinking MCP setup bypassed (MOSAIC_ALLOW_MISSING_SEQUENTIAL_THINKING=1)"
    else
      fail "sequential-thinking MCP setup failed (hard requirement)."
      exit 1
    fi
  fi
fi

if [[ -x "$SCRIPTS/mosaic-ensure-excalidraw" ]]; then
  "$SCRIPTS/mosaic-ensure-excalidraw" >/dev/null 2>&1 && ok "excalidraw MCP configured" || warn "excalidraw MCP setup failed (non-fatal)"
fi

if [[ "${MOSAIC_SKIP_SKILLS_SYNC:-0}" != "1" ]] && [[ -x "$SCRIPTS/mosaic-sync-skills" ]]; then
  "$SCRIPTS/mosaic-sync-skills" >/dev/null 2>&1 && ok "Skills synced" || warn "Skills sync failed (non-fatal)"
fi

if [[ -x "$SCRIPTS/mosaic-migrate-local-skills" ]]; then
  "$SCRIPTS/mosaic-migrate-local-skills" --apply >/dev/null 2>&1 && ok "Local skills migrated" || warn "Local skill migration failed (non-fatal)"
fi

if [[ -x "$SCRIPTS/mosaic-doctor" ]]; then
  "$SCRIPTS/mosaic-doctor" >/dev/null 2>&1 && ok "Health audit passed" || warn "Health audit reported issues — run 'mosaic doctor' for details"
fi

# Write version stamp AFTER everything succeeds
write_framework_version

# ── Summary ──────────────────────────────────────────────────
echo ""
echo -e "${GREEN}${BOLD}  Mosaic framework installed.${RESET}"
echo ""

if [[ ! -f "$TARGET_DIR/SOUL.md" ]]; then
  echo -e "  Run ${CYAN}mosaic init${RESET} to set up your agent identity."
  echo ""
fi